The present invention relates to a vinyl chloride resin, a chlorinated vinyl chloride resin and a method of producing the same, a chlorinated vinyl chloride resin pipe, a chlorinated vinyl chloride resin joint and a chlorinated vinyl chloride resin plate.
Vinyl chloride resins (hereinafter sometimes referred to also as xe2x80x9cPVCxe2x80x9d or xe2x80x9cPVC resinsxe2x80x9d) are used in various fields as materials having good mechanical strength, weathering resistance and chemical resistance. Since, however, PVC resins have the drawback of being inferior in shock resistance, various methods have been proposed to improve their shock resistance. Thus, for example, addition of a copolymer having rubber-like properties and/or high-level addition of an inorganic material, a metal powder or the like has been practiced.
Japanese Kokoku Publication Sho-44-453 discloses a method comprising blending, with PVC resins, a methyl methacrylate-butadiene-styrene copolymer (MBS copolymer) as a dispersoid. Japanese Kokai Publication Hei-02-20545 discloses a method comprising blending, with PVC resins, a chlorinated polyethylene (CPE resin) as a dispersoid.
However, when an MBS copolymer or a CPE resin is blended with PVC resins, the problem of lowered moldability arises, although the shock resistance is improved to a certain extent. Further, such a method comprising blending a copolymer having rubber-like properties with PVC resins pays attention only to the dispersoid but not to the PVC resins themselves, which are dispersion media, and accordingly the shock resistance improving effect is limited.
Furthermore, in many cases, loading materials, fillers, reinforcements and the like are incorporated in PVC resins for providing them with mechanical strength and functions. Therefore, PVC resins highly capable of dispersing other kinds of materials therein and allowing high level addition thereof and having good gelation properties are demanded. Further, since PVC resins excellent in gelation properties are generally excellent in high-speed moldability, PVC resins having good gelation properties as well are desired.
For improving such gelation properties and attaining high level loadability and dispersibility of materials of other kinds, it is necessary that the PVC resins be readily disintegrable and have micropores within resin particles with a high void content.
On the other hand, PVC resins are inferior in heat resistance. Therefore, chlorinated vinyl chloride resins (hereinafter referred to also as xe2x80x9cCPVCxe2x80x9d or xe2x80x9cCPVC resinsxe2x80x9d) have been developed which are produced by chlorinating PVC resins and thus improved in heat resistance.
While PVC resins have a low thermal deformation temperature and the upper limit temperature allowing their practical use is around 60 to 70xc2x0 C., hence they cannot be used in contact with hot water, CPVC resins have a thermal deformation temperature higher by 20 to 40xc2x0 C. as compared with PVC resins, so that they can be used in contact with hot water and are thus favorably used as materials of heat-resistant pipes and heat-resistant joints, typically for hot water supply, or of heat-resistant resin material plates for producing tanks or containers, for instance. Through the use of CPVC, the problem of rusting due to corrosion so far encountered with the conventional metal pipes, metal plates and the like has been liquidated.
However, since CPVC resins have a high thermal deformation temperature, a high temperature and great shearing force are required for effecting gelation in the step of molding/fabrication, tending to cause degradation and discoloration of the resins. CPVC resins thus have a narrow margin of moldability and they are often molded into products in an insufficient gelation state and, on such occasions, the products can hardly be said to have fully inherited the performance characteristics intrinsic in the material resins.
In addition to such improvement requirement concerning gelation properties, a higher level of heat resistance, too, is now required. In the case of heat-resistant pipes, heat-resistant joints and reservoirs for holding chemical liquids, for instance, they are liable to expand to the extent of undergoing deformation and fracture when high-temperature steam at 100xc2x0 C. or higher is generated as the result of, for instance, a failure in the operation of a safety device or upon introduction of a chemical liquid heated to 100xc2x0 C. or above. For passing a liquid or gas at 100xc2x0 C. or above through such heat-resistant pipes or heat-resistant joints or introducing a chemical liquid at 100xc2x0 C. or above into such chemical liquid reservoirs, the pipes and joints for hot water supply are required to have still higher levels of heat resistance and chemical resistance as compared with the conventional pipes and joints for hot water supply. They, in particular, are required to have high shock resistance such that they may withstand water hammer shocks. For that purpose, it is necessary that the gelation of CPVC resins be sufficient.
For solving such problems, Japanese Kokai Publication Sho-49-6080, for instance, discloses a method comprising chlorinating a PVC resin in the form of aggregates consisting of primary particles about 1 xcexcm in size as resulting from the use of a suspension stabilizer composed of an ionic emulsifier, a water-soluble metal salt and a water-soluble macromolecular dispersant (i.e. proposal for improving resin particles). This method indeed improves the gelation properties in the step of molding/fabrication but, the improvement is not yet satisfactory. In addition, a problem arises: a large amount of scale is formed in the step of polymerization and sticks to the polymerizer wall surface to thereby lessen the heat removing effect, hence work is required to remove said scale.
Japanese Kkai Publication Hei-04-81446 discloses a method of attaining a high thermal deformation temperature which comprises using a resin composition having a specific chlorine content and a shock resistance enhancer. However, the heat resistance attainable is still below the level intended to reach by us.
Japanese Kokai Publication Hei-05-132602 discloses a method of attaining high heat resistance which comprises blending a CPVC resin with a PVC resin so as to obtain a viscosity in a specific range (proposal-for improvement by resin blending) However, this method is only expected to bring about an improvement in heat resistance by about 3 to 4xc2x0 C. in terms of Vicat value as well as a certain extent of gelling performance improvement owing to the improvement in melt viscosity. The method can never satisfactorily attain the high levels of heat resistance and gelation properties which are aimed at by us.
Japanese Kokai Publication Hei-06-128320 discloses a method of chlorinating PVC-resins which comprises two steps (two-step chlorination method). This method is intended to produce highly heat-resistant CPVC resins by increasing the chlorine content to 70 to 75% by weight (proposal for improvement by high level chlorination). However, while this method can be expected to afford high heat resistance according to the chlorine content, no means is disclosed for preventing the gelation properties from predictably worsening as a result of high level chlorination and, accordingly, the method cannot provide practical levels of high heat resistance and gelation properties.
Japanese Kohyo Publication Sho-57-501285 discloses a method of producing highly heat-resistant CPVC resins by effecting the chlorination reaction under ultraviolet irradiation which method employing a chlorine pressure within the range of 25 to 100 psi (1.75 to 7 kg/cm2) and using resin particles restricted in porosity to 0.1 to 0.7 cc/g and in surface area to 0.7 to 2 m2/g. However, only the chlorination pressure is considered as the condition for attaining high heat resistance in this chlorination reaction. The ranges given for the porosity and surface area of resin particles are too broad and no preferred ranges are shown therefor. The CPVC resins obtained are thus mostly low in heat resistance. Further, that part of this technology which is claimed to be effective in the chlorination process is the preliminary permeation step called xe2x80x9csoakingxe2x80x9d prior to initiation of the chlorination reaction by ultraviolet irradiation but, under the conditions of this step, high heat resistance cannot be obtained.
According to Japanese Kokai Publication Hei-01-217008, the mean particle diameter and void ratio of a PVC resin in photochlorination under intermittent irradiation are restricted to respective specific ranges. By this proposal, it is intended that the chlorination reaction within resin particles be made uniform by promoting the diffusion of chlorine in a nonirradiation step. However, due to failure to take consideration of the surface profile (skin layer), the ready gelation tendency is not aimed at although the heat resistance of the product CPVC resin can be improved.
Janpanese Kohyo Publication Sho-57-501184 discloses a method of producing a chlorinated vinyl chloride resin which comprises, in carrying out the chlorination reaction under actinic rays irradiation using liquid chlorine as the main source of chlorine, using, as the PVC resin, a PVC resin occurring as granular resin particles having a mean particle size of 10 to 50 xcexcm, whose constituent element primary particles have a mean particle size of 0.05 to 5 xcexcm, and having a porosity of 0.2 to 0.3. The main concerns of this technology are the resin particle size and primary particle size in view of the possibility that the process of chlorine diffusion in the core of each PVC resin particle to be chlorinated might be the rate-determining step in the chlorination reaction of a PVC resin. However, the CPVC resin obtained shows only a small extent of improvement in heat resistance and in gelation properties. This is because, as reported in xe2x80x9cAIChE Journal, October 1988, Vol. 34, No. 10, pages 1683-1690xe2x80x9d, the diffusion of chlorine in the chlorination reaction is not determined by an elemental factor called primary particle size or grain size but is presumably governed by the agglomerate size resulting from agglomeration of primary particles.
However, the finding that the agglomerate size is predominating alone cannot make it possible to obtain CPVC resins excellent in heat resistance and gelation properties. The reason is that, since a dispersant is used in the step of suspension polymerization, grain particles of the PVC resin have a thick skin layer and the occurrence of this skin layer causes a decrease in gelation properties and further prevents the diffusion of chloride. Thus, for obtaining a CPVC resin excellent in heat resistance and gelation properties, it is necessary to pay attention to both the skin layer and agglomerate size. However, the technique of removing the skin layer from PVC resins and controlling the agglomerate size thereof is very difficult. As far as the prior art methods of producing CPVC resins are concerned, both have not been investigated.
Japanese Kokoku Publication Sho-45-30833 described that when the chlorination is carried out at a temperature of 55 to 80xc2x0 C. while feeding chlorine with an oxygen concentration of 0.05 to 0.35% by volume at a specified rate, CPVCs having good heat stability can be-obtained. Since, however, the reaction is carried out in the presence of a high concentration of oxygen and at a low temperature, the heat stability is not so markedly high, hence the product cannot tolerate long-time extrusion molding or injection molding.
Japanese Kokai Publication Hei-09-328518 proposes a method comprising carrying out the chlorination under ultraviolet irradiation using chlorine having an oxygen concentration of not more than 200 ppm. Since, however, the reaction is carried out at a low temperature by means of ultraviolet irradiation, any CPVC having remarkably good heat stability can not be obtained.
Further, Japanese Kokai Publication Hei-09-32822 proposes a method comprising carrying out the chlorination at 110 to 135xc2x0 C. while feeding chlorine containing 10 to 100 ppm of oxygen. Since the chlorination is carried out at a high temperature in the manner of thermal chlorination, CPVC resins excellent in heat stability can be obtained and the chlorination reaction can proceed smoothly. However, the voids in the interior of particles decrease under the influence of the thermal energy released upon the high temperature reaction, hence sufficient gelation will hardly take place in the step of molding/fabrication. For improving the workability, it is necessary to further cause heat generation from within particles under high temperature and high shearing conditions.
Thus, in the prior art, no high heat resistance PVCs or high heat resistance CPVCs having superior gelling performance and heat resistance characteristics are available nor pipes or joints made of a high heat resistance CPVC and having superior heat resistance, shock resistance and chemical resistance are obtainable. No high heat resistance CPVC resin plates excellent in heat resistance, shock resistance and chemical resistance are available, either.
Meanwhile, high heat resistance vinyl chloride resin moldings improved in heat resistance temperature have advantages over ordinary vinyl chloride resin articles in that they can stand against higher pressures when compared under the same morphological and temperature conditions and in that they can be used at higher temperatures when compared under the same pressure conditions.
Japanese Kokai Publication Hei-04-359928, for instance, proposes, as heat resistant vinyl chloride resin moldings, heat-resistant and hygienic pipes for hot water supply as produced from a chlorinated vinyl chloride resin (hereinafter referred to as xe2x80x9cCPVCxe2x80x9d) having a chlorine content of not less than 67.5% by weight as produced by chlorination of a vinyl chloride resin, together with a specific compounding additive.
However, the conventional heat-resistant vinyl chloride resins have a higher viscosity, hence their stress relaxation time is longer, as compared with the ordinary vinyl chloride resins and, therefore, the appearance of the moldings thereof is inferior in smoothness.
For providing moldings with smoothness, measures are generally taken to raise the temperature of the resin to be molded and the mold temperature and/or prolong the residence time in the mold. For providing heat-resistant vinyl chloride resin moldings with satisfactory smoothness, it is necessary to considerably raise the molding temperature and/or considerably prolonging the residence time in the mold, with the result, however, that the resin experiences a thermal history and becomes readily decomposable, which presents a problem concerning the long-run feature (continuous moldability) in some instances. For these reasons, any heat-resistant vinyl chloride resin moldings having both good smoothness and high heat resistance have not yet been put on the market.
On the other hand, piping materials for ultra pure water for plant use and like piping materials are required to have a smooth surface with the pipe inside surface unevenness reduced to a minimum so that the propagation of bacteria on the pipe inside surface can be inhibited.
When an attempt is made to increase the heat resistance of a raw material resin for molding for improving the reliability of those products or for extending the range of applications thereof, the smoothness of the moldings obtained is apt to be impaired. Therefore, it is conceivable to use a raw material resin improved in heat stability by addition of a metal compound, a stabilizer or the like and increase the molding temperature and/or prolong the residence time in the mold to thereby provide the products with surface smoothness. In such a field of use as piping materials for ultra pure water for plant use, however, limitations are imposed on the amounts of elution of impurities such as metal ions and TOC (total organic carbon) in order that the quality of ultra pure water may not be affected. Therefore, the use of metal compounds, stabilizers and the like is restricted. As a result, it is difficult, because of such problems as thermal decomposition and limited long run possibility, to provide surface smoothness by raising the molding temperature and/or prolonging the residence time in the mold.
Regarding this problem, Japanese Kokai Publication Hei-09-316267 discloses that piping materials for ultrapure water for plant use having good surface smoothness, while enabling long run production, can be formed by using a composition comprising a chlorinated vinyl chloride resin, organotin stabilizer, oxidized polyethylene wax, modifier, lubricant, processing aid and pigment and so on in specific proportions.
Further, heat-resistant piping materials for ultrapure water which can be readily cleaned by thermal sterilization have recently been demanded and the material used there is a chlorinated vinyl chloride resin. In molding pipes having a smooth and even surface, a lower degree of chlorination and a lower average degree of polymerization are advantageous. For providing heat resistance, however, the degree of chlorination should be above a certain level and, from the long-term creep characteristics and fatigue strength viewpoint, it is necessary to increase the average degree of polymerization.
On the other hand, when such piping materials are joined together using an adhesive, the solvent in the adhesive used may cause cracking on the pipe inside surface after joining (such cracking is called solvent cracking; hereinafter, solvent cracking is referred to as xe2x80x9cSCxe2x80x9d), which may lead to crack failure in some instances. The occurrence of this SC is probably influenced by the degree of chlorination and average degree of polymerization but what influences they have has not been fully understood.
For these reasons, those degree of chlorination and average degree of polymerization of a chlorinated vinyl chloride resin which might be molded into piping materials for ultrapure water for plant use having good smoothness, heat resistance and SC resistance combinedly have been unknown.
It is an object of the present invention to solve the problems mentioned above and, paying attention to the surface condition and internal condition of a vinyl chloride resin and to the distribution of chlorination therein, provide a vinyl chloride resin having a high void ratio and micropores in the interior of particles thereof and allowing high level filling and distribution of various compounding additives and a method of producing the same as well as to provide a chlorinated vinyl chloride resin having good gelation properties and heat resistance and a method of producing the same, to provide a chlorinated vinyl chloride resin having good heat resistance and manifesting good gelation properties and a method of producing the same, provide highly heat-resistant chlorinated vinyl chloride resin pipes and joints excellent in heat resistance and shock resistance and highly heat-resistant chlorinated vinyl chloride resin plates excellent in heat resistance, shock resistance and chemical resistance, and further provide heat-resistant vinyl chloride resin moldings highly reliable with respect to heat resistance and so forth, excellent in smoothness and having a good appearance as well as heat-resistant vinyl chloride resin pipes having high heat resistance, excellent in smoothness so that propagation of bacteria and the like inside them may be inhibited, and usable in pure water distribution systems or the like or heat-resistant vinyl chloride resin pipes having superior smoothness, heat resistance and SC resistance combinedly and usable as piping materials for ultrapure plant water and so forth.
In a first aspect, the invention provides a vinyl chloride resin as well as a chlorinated vinyl chloride resin and a method of producing the same.
In a first mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin,
said vinvl chloride resin having a BET specific surface area of 1.3 to 8 m2/g and a carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peakxc3x972/carbon element peak) of higher than 0.6 as determined by particle surface analysis by ESCA (electron spectroscopy for chemical analysis) (hereinafter referred to as xe2x80x9cInvention I-1xe2x80x9d).
In a second mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin according to Invention I-1
which satisfies the following relations (1) and (2):
xe2x88x923.9X+300xe2x89xa7Yxe2x89xa7xe2x88x923.9X+290xe2x80x83xe2x80x83(1)
xe2x88x923.2X+280xe2x89xa7Zxe2x89xa7xe2x88x923.2X+270xe2x80x83xe2x80x83(2)
wherein X is the chlorine content (% by weight) of the chlorinated vinyl chloride resin, Y is the amount (g) of methyl alcohol required for initiating precipitation of the chlorinated vinyl chloride resin when 3.0 g of the resin is completely dissolved in 60 g of tetrahydrofuran at 20xc2x0 C. and then methyl alcohol is gradually added to the solution to thereby cause precipitation of the resin, and Z is the amount (g) of methyl alcohol required to cause 80% by weight of the resin to precipitate (hereinafter referred to as xe2x80x9cInvention I-2xe2x80x9d).
In a third mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin
said vinyl chloride resin having a BET specific surface area of 1.3 to 8 m2/g and a carbon element-chlorine element 1S bond energy (eV) peak ratio [(chlorine element peak)xc3x972/carbon element peak] of higher than 0.6 as determined by particle surface analysis by electron spectroscopy for chemical analysis,
agglomerates being obtained by agglomeration of primary particles of the vinyl chloride resin,
the average particle diameter of the agglomerates being 1 to 7 xcexcm (hereinafter referred to as xe2x80x9cInvention I-3xe2x80x9d)
In a fourth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin according to Invention I-3
wherein the chlorination is carried out using a heat energy source (hereinafter referred to as xe2x80x9cInvention I-4xe2x80x9d).
In a fifth mode of embodiment of the first aspect of the invention, there is provided a vinyl chloride resin
having a BET specific surface area of 1.3 to 8 m2/g,
a carbon element-chlorine element 1S bond energy (eV) peak ratio [(chlorine element peak)xc3x972/carbon element peak] of higher than 0.6 as determined by particle surface analysis by electron spectroscopy for chemical analysis,
a void ratio of 27 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 
and an average pore size of 0.1 to 0.5 xcexcm (hereinafter referred to as xe2x80x9cInvention I-5xe2x80x9d).
In a sixth mode of embodiment of the first aspect of the invention, there is provided a vinyl chloride resin according to Invention I-5
wherein, in the pore volume distribution thereof as determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2, the percentage by volume (A1) of voids 0.001 to 0.1 xcexcm in size to the total volume of voids is 2 to 10% by volume (hereinafter referred to as xe2x80x9cInvention I-6xe2x80x9d).
In a seventh mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin according to Invention I-5 or Invention I-6 (hereinafter referred to as xe2x80x9cInvention I-7xe2x80x9d).
In an eighth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin, wherein said vinyl chloride resin has a BET specific surface area of 1.3 to 8 m2/g, a carbon element-chlorine element 1S bond energy (eV) peak ratio [(chlorine element peak)xc3x972/carbon element peak] of higher than 0.6 as determined by particle surface analysis by electron spectroscopy for chemical analysis and a void ratio of 27 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 
and, in the pore volume distribution thereof as determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2, the percentage by volume (A2) of voids 0.001 to 0.1 xcexcm in size to the total volume of voids is 2 to 30% by volume (hereinafter referred to as xe2x80x9cInvention I-8xe2x80x9d)
In a ninth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin according to Invention I-8
wherein, in the pore volume distribution of the vinyl chloride resin as determined by mercury porosimetry in the pressure range of 0 to 2, 000 kg/cm2, the percentage by volume (A1) of voids 0.001 to 0.1 xcexcm in size to the total volume of voids is 2 to 10% by volume,
and the percentage by volume (A2) of voids 0.001 to 0.1 xcexcm in size for the chlorinated vinyl chloride resin and the percentage by volume (A1) of voids 0.001 to 0.1 xcexcm in size for the vinyl chloride resin satisfy the following relation (1):
(A1)xc3x972xe2x89xa6(A2)xe2x80x83xe2x80x83(1)
(hereinafter referred to as xe2x80x9cInvention I-9xe2x80x9d).
In a tenth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin according to Invention I-8 or Invention I-9, wherein the percentage by volume (A2) of voids 0.001 to 0.1 xcexcm in size to the total volume of voids for the chlorinated vinyl chloride resin is 3 to 15% by volume (hereinafter referred to as xe2x80x9cInvention I-10xe2x80x9d)
In an eleventh mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin and
having a chlorine content of 60 to 72% by weight and a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2,
wherein, in the pore volume distribution thereof as determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2, the voids 0.001 to 0.1 xcexcm in size account for 2 to 15% relative to the total volume of voids (hereinafter referred to as xe2x80x9cInvention I-11xe2x80x9d).
In a twelfth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin
and having a chlorine content of 60 to 72% by weight,
a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 
and a BET specific surface area of 2 to 12 m2/g (hereinafter referred to as xe2x80x9cInvention I-12xe2x80x9d).
In a thirteenth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin
and having a chlorine content of 60 to 72% by weight and a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2,
wherein, in the pore volume distribution thereof as determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2, the voids 0.001 to 0.1 xcexcm in size account for 2 to 15% relative to the total volume of voids. and the absorbance (cell length 1 cm, measuring temperature 23xc2x0 C.) of a 1 g/kg tetrahydrofuran solution thereof is not more than 0.8 at the wavelength 235 nm (hereinafter referred to as xe2x80x9cInvention I-13xe2x80x9d).
In a fourteenth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin
and having a chlorine content of 60 to 72% by weight, a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 and a BET specific surface area of 2 to 12 m2/g
wherein the absorbance (cell length 1 cm, measuring temperature 23xc2x0 C.) of a 1 g/kg tetrahydrofuran solution thereof is not more than 0.8 at the wavelength 235 nm (hereinafter referred to as xe2x80x9cInvention I-14xe2x80x9d).
In a fifteenth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin and having a chlorine content of 60 to 72% by weight and a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm
wherein, in the pore volume distribution thereof as determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2, the voids 0.001 to 0.1xcexcm in size account for 2 to 15% relative to the total volume of voids
and the absorbance (cell length 1 cm, measuring temperature 23xc2x0 C.) of a 1 g/kg tetrahydrofuran solution thereof is not more than 0.2 at the wavelength 235 nm (hereinafter referred to as xe2x80x9cInvention I-15xe2x80x9d)
In a sixteenth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin
and having a chlorine content of 60 to 72% by weight, a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 and a BET specific surface area of 2 to 12 m2/g,
wherein the absorbance (cell length 1 cm, measuring temperature 23xc2x0 C.) of a 1 g/kg tetrahydrofuran solution thereof is not more than 0.2 at the wavelength 235 nm (hereinafter referred to as xe2x80x9cInvention I-16xe2x80x9d).
In a seventeenth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin
and having a chlorine content of 60 to 72% by weight and a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2,
wherein, in the pore volume distribution thereof as determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2, the voids 0.001 to 0.1 xcexcm in size account for 2 to 15% relative to the total volume of voids
and the following relations (1) and (2) are satisfied:
xe2x88x923.9X+305xe2x89xa7Yxe2x89xa7xe2x88x923.9X+300xe2x80x83xe2x80x83(1)
xe2x88x923.2X+270xe2x89xa7Zxe2x89xa7xe2x88x923.2X+265xe2x80x83xe2x80x83(2)
where X is the chlorine content (% by weight) of the chlorinated vinyl chloride resin and Y is the amount (g) of methyl alcohol required for initiating precipitation of the chlorinated vinyl chloride resin when 3.0 g of the resin is completely dissolved in 60 g of tetrahydrofuran and then methyl alcohol is gradually added to the solution to thereby cause precipitation of the resin, and Z is the amount (g) of methyl alcohol required to cause 80% by weight of the resin to precipitate (hereinafter referred to as xe2x80x9cInvention I-17xe2x80x9d).
In an eighteenth mode of embodiment of the first aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin
and having a chlorine content of 60 to 72% by weight, a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 and a BET specific surface area of 2 to 12 m2/g
wherein the following relations (1) and (2) are satisfied:
xe2x88x923.9X+305xe2x89xa7Yxe2x89xa7xe2x88x923.9X+300xe2x80x83xe2x80x83(1)
xe2x88x923.2X+270xe2x89xa7Zxe2x89xa7xe2x88x923.2X+265xe2x80x83xe2x80x83(2)
where X is the chlorine content (% by weight) of the chlorinated vinyl chloride resin,
Y is the amount (g) of methyl alcohol required for initiating precipitation of the chlorinated vinyl chloride resin when 3.0 g of the resin is completely dissolved in 60 g of tetrahydrofuran at 20xc2x0 C. and then methyl alcohol is gradually added to the solution to thereby cause precipitation of the resin, and Z is the amount (g) of methyl alcohol required to cause 80% by weight of the chlorinated vinyl chloride resin to precipitate (hereinafter referred to as xe2x80x9cInvention I-18xe2x80x9d).
In a nineteenth mode of embodiment of the first aspect of the invention, there is provided a method of producing a chlorinated vinyl chloride resin by chlorination of a vinyl chloride resin
wherein said vinyl chloride resin has a BET specific surface area of 1.3 to 8 m2/g and a carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peakxc3x972/carbon element peak) of higher than 0.6 as determined by particle surface analysis by ESCA (electron spectroscopy for chemical analysis)
and said chlorination is carried out by introducing liquid chlorine or gaseous chlorine into a reaction vessel containing the vinyl chloride resin in a state suspended in an aqueous medium at a reaction temperature within the range or 70 to 135xc2x0 C. (hereinafter referred to as xe2x80x9cInvention I-19xe2x80x9d).
In a twentieth mode of embodiment of the first aspect of the invention, there is provided a method of producing a chlorinated vinyl chloride resin according to Invention I-19,
wherein the vinyl chloride resin has a BET specific surface area of 1.5 to 5 m2/g (hereinafter referred to as xe2x80x9cInvention I-20xe2x80x9d).
In a twenty-first mode of embodiment of the first aspect of the invention, there is provided a method of producing a chlorinated vinyl chloride resin according to Invention I-19 or Invention I-20,
wherein the above-mentioned peak ratio of the vinyl chloride resin as determined by particle surface analysis by ESCA is above 0.7 (hereinafter referred to as xe2x80x9cInvention I-21xe2x80x9d)
In a second aspect, the invention provides a chlorinated vinyl chloride resin and a method of producing the same.
In a first mode of embodiment of the second aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin and having a chlorine content of 72 to 76% by weight and a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 
wherein, in the pore volume distribution thereof as determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2, the voids 0.001 to 0.1 xcexcm in size account for 2 to 1S% relative to the total volume of voids (hereinafter referred to as xe2x80x9cInvention II-1xe2x80x9d).
In a second mode of embodiment of the second aspect of the invention, there is provided a chlorinated vinyl chloride resin obtainable by chlorination of a vinyl chloride resin and having a chlorine content of 72 to 76% by weight, a void ratio of 30 to 40% by volume as determined by mercury porosimetry at a pressure of 2,000 kg/cm2 and a BET specific surface area of 2 to 12 m2/g (hereinafter referred to as xe2x80x9cInvention II-2xe2x80x9d).
In a third mode of embodiment of the second aspect of the invention, there is provided a chlorinated vinyl chloride resin according to Invention II-1 or Invention II-2
having a carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peakxc3x972/carbon element peak) of higher than 0.6 as determined by particle surface analysis by ESCA (electron spectroscopy for chemical analysis) (hereinafter referred to as xe2x80x9cInvention II-3xe2x80x9d).
In a fourth mode of embodiment of the second aspect of the invention, there is provided a method of producing a chlorinated vinyl chloride resin by chlorination of a vinyl chloride resin
wherein the vinyl chloride resin has a BET specific surface area of 1.3 to 8 m2/g and a carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peak/carbon element peak) of higher than 0.6 as determined by particle surface analysis by ESCA (electron spectroscopy for chemical analysis)
and said chlorination is carried out until attainment of a chlorine content of 72 to 76% by weight by introducing liquid chlorine or gaseous chlorine into a reaction vessel containing the vinyl chloride resin in a state suspended in an aqueous medium at a temperature within the range of 70 to 135xc2x0 C. (hereinafter referred to as xe2x80x9cInvention II-4xe2x80x9d).
In a third aspect, the invention provides a high heat resistant chlorinated vinyl chloride resin pipe, a high heat resistant chlorinated vinyl chloride resin joint and a chlorinated vinvl chloride resin plate.
In a first mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-1xe2x80x9d).
In a second mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-2xe2x80x9d).
In a third mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having avicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to Jis K 7206 (hereinafter referred to as xe2x80x9cInvention III-3xe2x80x9d).
In a fourth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-4xe2x80x9d).
In a fifth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-5xe2x80x9d).
In a sixth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-6xe2x80x9d).
In a seventh mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-7xe2x80x9d).
In an eighth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-8xe2x80x9d).
In a ninth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin pipe having a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-9xe2x80x9d).
In a tenth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-10xe2x80x9d)
In an eleventh mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat""softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-11xe2x80x9d).
In a twelfth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-12xe2x80x9d).
In a thirteenth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-13xe2x80x9d).
In a fourteenth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-14xe2x80x9d).
In a fifteenth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-15xe2x80x9d).
In a sixteenth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-16xe2x80x9d).
In a seventeenth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-17xe2x80x9d).
In an eighteenth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin joint having a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-18xe2x80x9d).
In a nineteenth mode of embodiment of the third aspect of the invention, there Is provided a chlorinated vinyl chloride resin plate having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-19xe2x80x9d)
In a twentieth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin plate having a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-20xe2x80x9d).
In a twenty-first mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin plate having a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 (hereinafter referred to as xe2x80x9cInvention III-21xe2x80x9d).
In a twenty-second mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin plate having a Vicat-softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-22xe2x80x9d).
In a twenty-third mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin plate having a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-23xe2x80x9d).
In a twenty-fourth mode of embodiment of the third aspect of the invention, there is provided a chlorinated vinyl chloride resin plate having a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111 (hereinafter referred to as xe2x80x9cInvention III-24xe2x80x9d).
In a fourth aspect, the invention provides a heat-resistant vinyl chloride resin molding and a heat-resistant vinyl chloride resin pipe.
In a first mode of embodiment of the fourth aspect of the invention, there is provided a heat-resistant vinyl chloride resin molding having a heat resistance temperature of not lower than 125xc2x0 C. and a surface roughness Rmax of not more than 0.5 xcexcm (hereinafter referred to as xe2x80x9cInvention IV-1xe2x80x9d).
In a second-mode of embodiment of the fourth aspect of the invention, there is provided a heat-resistant vinyl chloride resin molding according to Invention IV-1
having a decomposition time of not shorter than 30 minutes as determined in an oven at 200xc2x0 C. (hereinafter referred to as xe2x80x9cInvention IV-2xe2x80x9d).
In a third mode of embodiment of the fourth aspect of the invention, there is provided a heat-resistant vinyl chloride resin pipe
having a heat resistance temperature of not lower than 125xc2x0 C. and a surface roughness Rmax of not more than 0.5 xcexcm (hereinafter referred to as xe2x80x9cInvention. IV-3xe2x80x9d).
In a fourth mode of embodiment of the fourth aspect of the invention, there is provided a heat-resistant vinyl chloride resin pipe according to Invention IV-3
having a decomposition time of not shorter than 30 minutes as determined in an oven at 200xc2x0 C. (hereinafter referred to as xe2x80x9cInvention IV-4xe2x80x9d).
In a fifth mode of embodiment of the fourth aspect of the invention, there is provided a heat-resistant vinyl chloride resin pipe obtainable by molding a heat-resistant vinyl chloride resin,
said heat-resistant vinyl chloride resin being obtained by chlorination of a vinyl chloride resin having a viscosity average degree of polymerization of 900 to 1,100 to a chlorine content of 66.0 to 67.5% by weight (hereinafter referred to as xe2x80x9cInvention IV-5xe2x80x9d).
In a sixth mode of embodiment of the fourth aspect of the invention, there is provided a heat-resistant vinyl chloride resin pipe according to Invention IV-3, Invention IV-4 or Invention IV-5 which is to serve as a piping material for pure water distribution (hereinafter referred to as xe2x80x9cInvention IV-6xe2x80x9d).
In the following, the invention is described in-detail.
In the present specification, the terms xe2x80x9cchlorine contentxe2x80x9d and xe2x80x9cdegree of chlorinationxe2x80x9d are to be construed as synonymous, the terms xe2x80x9cPVCxe2x80x9d, xe2x80x9cPVC resinxe2x80x9d and xe2x80x9cvinyl chloride resinxe2x80x9d are to be construed as synonymous, and the terms xe2x80x9cCPVCxe2x80x9d, xe2x80x9cCPVC resinxe2x80x9d and xe2x80x9cchlorinated vinyl chloride resinxe2x80x9d are to be construed as synonymous.
In the present specification, the expression xe2x80x9c60-772% by weightxe2x80x9d, when used with respect to the chlorine content, means xe2x80x9cnot less than 60% by weight but less than 72% by weightxe2x80x9d.
The first aspect of the invention is first described in detail.
With those chlorinated vinyl chloride resins produced by chlorinating conventional vinyl chloride resins, no attention has been paid to the surface condition and interior condition of vinyl chloride particles in vinyl chloride resin chlorination and, accordingly, no attention has been paid to the distribution of chlorination in the chlorinated vinyl chloride resin obtained. The present invention provides a chlorinated vinyl chloride resin having good gelation properties and heat resistance by paying due attention to the surface condition and interior condition of vinyl chloride particles and further to the distribution of chlorination in the chlorinated vinyl chloride resin to be obtained.
The PVC resin of the invention is a resin produced by polymerizing, by a method known in the art, monomeric vinyl chlorine alone or a mixture of monomeric vinyl chloride and another or other monomers copolymerizable with monomeric vinyl chloride. The other monomers copolymerizable with monomeric vinyl chloride are not particularly restricted but include, among others, alkyl vinyl esters such as vinyl acetate; xcex1-monoolefins such as ethylene and propylene; vinylidene chloride; styrene and the like. These may be used singly or two or more of them may be used in combination.
The average degree of polymerization of the above PVC resin is not critical but may be within the conventional range of 400 to 3,000.
The PVC resin of the invention has a BET specific surface area of 1.3 to 8 m2/g. When it is less than 1.3 m2/g, the number of micropores not greater than 0.1 xcexcm in the interior of PVC resin particles is not sufficient for the chlorination to proceed uniformly in the step of chlorination, so that the heat resistance of the product CPVC resin is not improved. When it is in excess of 8 m2/g, the heat resistance of PVC resin particles themselves decreases. Hence, the above range is critical, and 2 to 6 m2/g is preferred.
The carbon element-chlorine element IS bond energy (eV) peak ratio [(chlorine element peak)xc3x972/carbon element peak] as found in particle surface analysis by electron spectroscopy for chemical analysis (ESCA) of the PVC resin of the invention is in excess of 0.6. When it is 0.6 or below, the ready gelling properties of the PVC resin itself may be impaired and/or problems may arise with respect to the moldability/fabricability of the product CPVC resin, presumably due to adsorption of a dispersant and/or like additive on the surface of PVC resin particles. Further, the rate of chlorination becomes slow at the late stage of chlorination. The above range is thus critical. Preferably, it is above 0.7.
Among PVC resins the above-defined peak ratio of which is above 0.6, there exist PVC resin small in outer covering (referred to as xe2x80x9cskinxe2x80x9d) area on the surface of a PVC resin particles with the fine structure of the interior thereof (primary particles) being exposed (such resin is referred to as xe2x80x9cskinless PVC resinxe2x80x9d). At the same energy ratio, a skinless PVC resin is preferably used.
The element occurrence ratio in the chemical structure of the PVC resin of the invention is chlorine element:carbon element =1:2 (without considering the terminal structure and branching) and the above-mentioned peak ratio (chlorine element peak xc3x972/carbon element peak) at the 1S bond energy value (eV) has a value of 0 to 1. The peak ratio value of 0 means that the surface of vinyl chloride resin particles is covered with some chlorine-free substance other than a vinyl chloride resin, while the peak ratio value of 1 means that the surface of PVC resin particles is wholly covered with vinyl chloride components alone.
The PVC resin of the invention has a void ratio of 27 to 40% by volume relative to the volume of PVC resin particles as determined by mercury porosimetry at a pressure of 2,000 kg/cm2. When it is less than 27% by volume, chlorine cannot diffuse into resin voids to a sufficient extent during the chlorination reaction, hence the chlorination degree distribution becomes excessive, resulting in poor moldability/fabricability. There is another drawback, namely a prolonged chlorination reaction time is required. When it is above 40% by volume, the biting of the screw becomes worse in the step of molding and poor gelation results. The void ratio is thus restricted to the above range and preferably is 30 to 37% by volume.
The PVC resin of the invention has an average pore size of 0.1 to. 0.5 xcexcm. When it is less than 0.1 xcexcm, gaps are too narrow to achieve the desired improvement in high-level filling of inorganic materials, for instance, and, in the chlorination reaction, the gaps will not effectively serve in the chlorination reaction, namely chlorine cannot diffuse to a sufficient extent but the chlorination distribution within resin particles becomes excessively uneven, with the result that the CPVC obtained has poor heat resistance and a prolonged time is required for the chlorination reaction. When it is in excess of 0.5 xcexcm, the dispersibility of inorganic materials, among others, cannot be improved. Further, in the chlorination reaction, chlorine cannot diffuse throughout PVC resin particles but the chlorination distribution within resin particles becomes excessively uneven, hence the CPVC resin obtained has poor heat resistance.
The average pore size referred to above is a numerical value to be measured for more quantitatively defining the voids in PVC resin particles. It can be measured by mercury porosimetry within the pressure range of 0 to 2,000 kg/cm2. Since the void pore size in resin particles is a function of the pressure of mercury for filling void pores with the resin, the volume distribution of void pore sizes can be measured by continuously measuring the filling pressure and mercury weight. The average pore size in question can be calculated from the void pore size distribution measured in that manner.
For the above PVC resin, the volume percentage (A1) of voids 0.001 to 0.1 xcexcm in size relative to the total void volume in the pore volume distribution measured by mercury porosimetry within the pressure range of 0 to 2,000 kg/cm2 is preferably 2 to 10% by volume, although it is not particularly restricted.
When the void volume percentage (A1) for the range of 0.001 to 0.1 xcexcm is less than 2% by volume based on the total void volume, the proportion of microporous voids which resin particles have becomes decreased and the diffusion of chlorine may not be effected in a balanced manner in some instances. Thus, the diffusion of chlorine into those regions in the interior of resin particles where the void pore size is small may not proceed smoothly and the chlorination degree distribution within resin particles may become too large accordingly. When it is in excess of 10% by volume, the diffusion of chlorine into those regions in the interior of particles where the void pore size is small may proceed excessively, the chlorine supply itself cannot catch up with the diffusion and, as a result, the chlorination degree distribution within resin particles may become excessive, too. A more preferred range is 3 to 7% by volume.
The PVC resin of the invention can be obtained, for example, by suspension polymerization in an aqueous medium containing partially saponified polyvinyl acetate with a high saponification degree (60 to 90 mole percent) or low saponification degree (20 to 60 mole percent), or both, a higher fatty acid ester or the like as the dispersant, and an anionic emulsifier, a nonionic emulsifier or the like as the emulsifier.
The polymerizer (pressure-resistantautoclave) which can be used in producing the above PVC resin by polymerization is not particularly restricted in shape and structure but may be any of those conventionally used in PVC resin polymerization, for instance. The agitating blades are not particularly restricted but include those in general use, such as Pfaudler blades, paddle blades, turbine blades, fan turbine blades and bull margin blades, among others. Pfaudler blades are judiciously used, however, and the combined use of baffle plates is not particularly restricted.
Upon chlorination, the PVC resin of the invention can give CPVC resins excellent in gelation properties and heat resistance.
The chlorinated vinyl chloride resin of Invention I-2 preferably satisfies the following relations (1) and (2):
xe2x88x923.9X+300xe2x89xa7Yxe2x89xa7xe2x88x923.9X+290xe2x80x83xe2x80x83(1)
xe2x88x923.2X+280xe2x89xa7Zxe2x89xa7xe2x88x923.2X+270xe2x80x83xe2x80x83(2)
wherein X is the chlorine content (% by weight) of the chlorinated vinyl chloride resin, Y is the amount (g) of methyl alcohol required for initiating precipitation of the chlorinated vinyl chloride resin when 3.0 g of the resin is completely dissolved in 60 g of tetrahydrofuran at 20xc2x0 C. and then methyl alcohol is gradually added to the solution to thereby cause precipitation of the resin, and Z is the amount (g) of methyl alcohol required to cause 80% by weight of the resin to precipitate.
With the addition of methyl alcohol after complete dissolution of the chlorinated vinyl chloride resin in tetrahydrofuran, that fraction of the chlorinated vinyl chloride resin dissolved which is high in chlorination percentage begins to precipitate out. The above defined Y (amount of methyl alcohol required for initiating precipitation of the chlorinated vinyl chloride resin) is an indicator showing the occurrence of a high chlorination percentage resin fraction, and Z (total amount of methyl alcohol required to cause 80% by weight of the chlorinated vinyl chloride resin to precipitate) is an indicator showing the occurrence of a low chlorination percentage resin fraction. The chlorinated vinyl chloride resin satisfying the above relations (1) and (2) has excellent gelation properties, namely good workability, and high heat resistance.
For the chlorinated vinyl chloride resin according to Invention 1-3, the average diameter of agglomerates each resulting from agglomeration of primary particles of the vinyl chloride resin is 1 to 7 xcexcm.
When it is less than 1 xcexcm, the scale adhesion to the polymerizer wall increases and produces an increased amount of a finer resin powder fraction in the step of chlorinated vinyl chloride resin production, causing troubles in handling. When it is greater than 7 xcexcm, the diffusion of chlorine in the step of chlorination suddenly slows down and the diffusion becomes a rate-determining step for the chlorination reaction, so that the chlorination degree distribution becomes too broad and the chlorinated vinyl chloride resin obtained can no more be expected to have an improved level of heat resistance. Furthermore, much energy is required for disintegrating agglomerate particles, hence the gelation properties of the chlorinated vinyl chloride resin cannot be improved. The above range is thus critical. A preferred range is 1.5 to 5 xcexcm. The agglomerate diameter can be measured by observation under a commercial transmission electron microscope and photography, for instance.
It is generally known that vinyl chloride resin particles have similar hierarchic structures (xe2x80x9cPolyvinyl Chloride Resins xe2x80x94Fundamentals and Applicationsxe2x80x9d, pages 214-218, edited by Kinki Chemical Society Vinyl Section, published 1988 by Nikkan Kogyo Shimbunsha) The above agglomerates belong to the above hierarchic structures and each is a mass of primary particles collected together by weak bonding.
The vinyl chloride resin having the above-mentioned BET specific surface area, IS bond energy (eV) peak ratio and average agglomerate diameter can be obtained, for example by suspension polymerization in an aqueous medium containing high saponification degree (60 to 90 mole percent) polyvinyl acetate or low saponification degree (20 to 60 mole percent) polyvinyl acetate, or both, a higher fatty acid ester or the like as the dispersant, and an anionic emulsifier, nonionic emulsifier or the like as the emulsifier.
The PVC resin to be used in the production of the CPVC resin according to.Invention I-6 has a BET specific surface area of 1.3 to 8 m2/g, a carbon element-chlorine element 1S bond energy (eV) peak ratio [(chlorine element peak)xc3x972/carbon element peak] of higher than 0.6 as determined by particle surface analysis by electron spectroscopy for chemical analysis and a void ratio of 27 to 40% by volume as determined by mercury porosimetry at the pressure 2,000 kg/cm2. Suited for use as such PVC resin is the PVC resin according to Invention I-5.
The CPVC resin according to Invention I-6 is produced by chlorinating the above PVC resin. For the CPVC resin, the percentage by volume (A2) of voids 0.001 to 0.1 gm in size to the total volume of voids of the CPVC resin is 2 to 30% by volume in the pore volume distribution determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2. When it is less than 5% by volume, the frictional heat generation by shearing in the interior of particles takes place with difficulty, hence the gelation state in the step of molding is insufficient. When it is in excess of 30%, violent local heat generation occurs and unfavorably causes decomposition in the step of molding. Preferably, it is 10 to 25% by volume, more preferably 3 to 15% by volume.
It is preferred that the percentage of voids 0.001 to 0.1 xcexcm in size (A2) of the above CPVC resin and the percentage of voids 0.001 to 0.1 xcexcm in size (A1) of the PVC resin satisfy the following relation (1):
(A1)xc3x972xe2x89xa6(A2)xe2x80x83xe2x80x83(1).
When the percentage of voids 0.001 to 0.1 xcexcm in size (A2) of the above CPVC resin does not satisfy the above relation (1) the moldability of the CPVC resin may fail to reach a required level in certain instances.
The method of chlorinating the PVC resin used in accordance with the invention is not particularly restricted. It is necessary, however, to maintain the porosity and high void content of the PVC resin and, therefore, the chlorination is preferably effected by contacting chlorine with the above PVC resin in a suspended state. In carrying out the chlorination in a suspended state, it is also possible to effect the chlorination by blowing chlorine directly into the very suspension, without separating the PVC resin obtained by suspension polymerization from the aqueous medium.
The above chlorination in a suspended state can be carried out, for example, in the manner of photochemical chlorination by irradiating the reaction product with light, or can be carried out by exciting resin bonds and/or chlorine by heating. The source of light for causing chlorination by light energy is not particularly restricted but mention may be made of ultraviolet rays, and visible light from a mercury vapor lamp, arc lamp, incandescent lamp, fluorescent lamp or carbon arc, for instance. In particular, ultraviolet rays are effective. The method of heating for causing chlorination by thermal energy is not particularly restricted but mention may be made of exterior jacket heating through the reactor wall, internal jacket heating and heating by blowing steam into the reactor, among others. Generally, the exterior jacket system or internal jacket system is effective.
Among the chlorination methods mentioned above, the one comprising resin bond and/or chlorine excitation by thermal energy to thereby promote the chlorination is preferred. The reason is as follows. The matters of special concern in the present invention are the void ratio and pore distribution of the resin particles, in particular the distribution of voids occurring within the particles in a three-dimensional hierarchic manner. For attaining uniform chlorination, it is necessary to attain uniformity in chlorine diffusion as well as in chlorination reaction. While thermal energy acts uniformly to the inside of particles, light irradiation energy acts only on the surface of resin particles, with the result that the chlorination reaction necessarily proceeds predominantly on the surface of resin particles. Therefore, for realizing the chlorination reaction uniformly with respect to both diffusion and reaction, it is preferably to carry out the chlorination reaction by utilizing thermal energy.
When the above chlorination is effected by means of heating, the reaction is preferably carried out at 70 to 135xc2x0 C. When the reaction is carried out at above 135xc2x0 C., the hierarchic structure of the interior of particles swells and softens and pores are filled up at the early stage of reaction and, therefore, the resin after chlorination will have poor moldability/fabricability. At below 70xc2x0 C., the rate of reaction becomes slow. For increasing the rate of reaction, it is necessary to add a larger amount of an organic catalyst. However, this worsens the heat stability of the CPVC resin obtained, hence is undesirable from the moldability/fabricability viewpoint. A more preferred temperature is within the range of 90 to 125xc2x0 C.
The aqueous medium to be used in the above chlorination in a suspended state may contain a small amount of a ketone such as acetone or methyl ethyl ketone and further, necessary, a small amount of a chlorine-containing solvent such as hydrochloric acid, trichloroethylene and carbon tetrachloride may be added.
In the above chlorination step, the chlorine content of the product CPVC resin is preferably adjusted to 60 to 72% by weight.
The PVC resin of the invention and the CPVC resin of the invention can be hot-blended or cold-blended with appropriate amounts of additives such as an shock resistance improver, heat stabilizer, auxiliary stabilizer, lubricant, processing aid, filler, pigment, plasticizer and/or the like, using a Henschel mixer, ribbon mixer or Banbury mixer, for instance.
The above shock resistance improver is not particularly restricted but may be any of those known in the art. For example, a copolymer having rubber-like properties are suited for use. The copolymer having rubber-like properties is not particularly restricted but includes, among others, ethylene-vinyl acetate copolymers (EVA), chlorinated polyethylene (CPE), acrylonitrile-butadiene-styrene copolymers (ABS), methyl methacrylate-butadiene-styrene copolymers (MBS), ethylene-propylene copolymers (EPR), ethylene-propylene-diene monomer copolymers (EPDM) and acrylonitrile-butadiene copolymers (NBR). Among these, methyl methacrylate-butadiene-styrene copolymers (MBS) and chlorinated polyethylene. (CPE) are preferred.
The above methyl methacrylate-butadiene-styrene copolymers (MBS) may be commercial ones. From the shock resistance improvement viewpoint, however, those-having a butadiene content of 30 to 60% by weight are preferred. The chlorinated polyethylene (CPE) may be a commercial product as well. From the shock resistance improvement viewpoint, however, one having a chlorine content of 30 to 50% by weight is preferred.
The above shock resistance improver is used at an addition amount appropriately selected according to the required level of shock resistance. Preferably, it is used in an amount of 1 to 70 parts by weight, more preferably 2 to 35 parts by weight, per 100 parts by weight of the PVC resin of the invention or the CPVC resin of the invention.
The above heat stabilizer is not particularly restricted but includes, among others, organotin compounds such as dimethyltin mercaptides, dibutyltin mercaptides, dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, dioctyltin maleate polymer, dibutyltin laurate and dibutyltin laurate polymer; lead compounds such as lead stearate, dibasic lead phosphite and tribasic lead sulfate; calcium-zinc stabilizers, barium-zinc stabilizers and barium-cadmium stabilizers.
The above auxiliary stabilizer is not particularly restricted but includes, among others, epoxi-dized soybean oil, epoxidized linseed oil, epoxidized tetrahydrophthalate, epoxidized polybutadiene and phosphate esters.
The above lubricant is not particularly restricted but includes, among others, montanic acid wax, paraffin wax, polyethylene wax, stearic acid, stearyl alcohol and butyl stearate.
The above processing aid is not particularly restricted but includes, among others, acrylic processing aids, which are alkyl acrylate/alkyl methacrylate copolymers having a weigh average molecular weight of 100,000 to 2,000,000, for example n-butyl acrylate/methyl methacrylate copolymers and 2-ethylhexyl acrylate/methyl methacrylate/butyl methacrylate copolymers.
The above filler is not particularly restricted but includes, among others, calcium carbonate and talc.
The above pigment is not particularly restricted but includes, among others, organic pigments such as azo, phthalocyanine and threne pigments and dye lakes; and inorganic pigments such as oxide type, molybdenum chromate type, sulfides-selenide type, and ferrocyanide type.
The above plasticizer is added for improving the moldability/fabricability. The plasticizer is not particularly restricted but includes, among others, dibutyl phthalate, di-2-ethylhexyl phthalate and di-2-ethylhexyl adipate.
The resin composition obtained by compounding the PVC resin of the invention or the CPVC resin of the invention with various ingredients can be molded by any of the conventional molding methods, for example by extrusion molding, calender molding, contour molding or press molding, to give moldings.
The technical core of the invention is based on the following findings. Thus, it is known in the art that PVC resin particles have similar hierarchic structures (xe2x80x9cPolyvinyl Chloride Resinsxe2x80x94Fundamentals and Applicationsxe2x80x9d, pages 214-18, edited by Kinki Chemical Society Vinyl Section, published 1988 by Nikkan Kogyo Shimbunsha). However, the art has no knowledge of the hierarchic structure of voids thereof.
As a result of intensive investigations, the present inventors found that the voids, too, can have a hierarchic structure. In particular, the hierarchic structure of the voids was found markedly when the BET specific surface area is within the range of 1.3 to 8 m2/g and the peak ratio found by ESCA is in excess of 0.6. Based on this finding, it was found that a specific void ratio range and a specific average pore size range are best suited. Although no adequate means are available to evaluate and analyze the actual progress of the chlorination reaction and the chlorination degree distribution, those CPVC resins obtained by chlorinating such a PVC resin show good characteristics when evaluated for heat resistance (Vicat softening temperature), workability (gelling temperature) and heat stability and, therefore, the chlorination degree distribution is within a preferred range.
In other words, the present invention presents those structural factors of a PVC resin which make it possible for chlorine to diffuse neither excessively nor insufficiently from the circumference to the central part of particles in the chlorination reaction.
The CPVC resin of the invention is intended to be improved in heat resistance by chlorination of a PVC resin and, at the same time, is intended to be improved in moldability/fabricability by causing both the PVC resin and the CPVC resin obtained after chlorination to have particular intraparticle structure characteristics. Furthermore, it was found that when the void volume (A1) of pores having a pore size of 0.001 to 0.1 xcexcm in the pore distribution of the PVC resin is within the range of 2 to 10% by volume, the pore volume in the pore distribution range of 0.001 to 0.1 xcexcm in pore size is more increased. This finding has now led to completion of Invention I-8. This noteworthy phenomenon is presumably related with the specific surface area of the PVC resin and the particle structure specified by ESCA.
In the following, the eleventh mode of embodiment of the invention in accordance with the first aspect thereof (Invention I-11) and the further modes of embodiment of the invention are described in further detail.
The PVC to be used in the production of the CPVC of the invention is preferably the PVC obtained by the production method described in Japanese Kokai Publication Hei-08-120007, Japanese Kokai Publication Hei-08-295701, Japanese Kokai Publication Hei-09-132612 or Japanese Kokai Publication Hei-09-227607.
The present invention is defined by a chlorine content, a void ratio and a void volume for pores of 0.001 to 0.1 xcexcm, each specified above.
The CPVC of the invention has a chlorine content of 60 to 72% by weight. In the present specification, the expression xe2x80x9c60 to 72% by weightxe2x80x9d means that the content is not less than 60% by weight but less than 72% by weight. When the chlorine content is less than 60% by weight, the improvement in heat resistanceis unsatisfactory. When it is 72% by weight or above, the molding becomes difficult and the gelation becomes insufficient. A preferred range is 63 to 70% by weight.
The CPVC of the invention has a void ratio of 30 to 40% by volume. The void ratio is the one measured by mercury porosimetry at the pressure 2,000 kg/cm2. When the void ratio is less than 30%, the gelation is retarded in the step of molding, which is undesirable from the moidability/fabricability viewpoint. When it exceeds 40% by volume, the biting by the screw becomes insufficient and poor gelation results. A preferred range is 31 to 38% by volume.
For the CPVC of the invention, the void volume for pores of 0.001 to 0.1 xcexcm in the pore volume distribution determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2 is 2 to 15% by volume relative to the total void volume. The void pore size in resin particles is a function of the pressure of mercury filled into void pores of the resin. Therefore, the pore size distribution can be determined by continuously measuring the filling pressure and mercury weight. When the void volume for the range 0.001 to 0.1 xcexcm is less than 2% by volume relative to the total void volume, the proportion of micropores in the interior of particles is insufficient, hence the product is inferior in gelation propety in the step of molding. When it is above 15% by volume, the diffusion of chlorine in the step of chlorination cannot be effected in a balanced manner but the chlorination degree distribution within particles becomes excessive, hence no good heat stability can be attained. A preferred void volume for the range 0.001 to 0.1 xcexcm is 3 to 13% by volume relative to the total void volume.
Invention I-12 is defined by a chlorine content, a void ratio and a BET specific surface area, each specified.
The chlorine content and void ratio of the CPVC of invention I-12 are as mentioned above for Invention I-11.
The CPVC of Invention I-12 has a BET specific surface area of 2 to 12 m2/g. When the BET specific surface area is less than 2 m2/g, the proportion of micropores in the interior of particles is insufficient, so that intraparticle melting becomes difficult to occur in the step of molding, hence the gelation performance gets worse. When the BET specific surface area is above 12 m2/g, the generation of heat of friction from the inside occurs rapidly and the heat stability in the step of molding becomes decreased. A preferred BET specifics surface area is 3 to 10 m2/g.
Invention I-13 is defined by a chlorine content, a void ratio, a void volume for 0.001 to 0.1 xcexcm and an absorbance at 235 nm, each specified.
The chlorine content, void ratio and void volume for 0.001 to 0.1 xcexcm of the CPVC according to Invention I-13 are the same as those according to Invention I-11.
The absorbance (cell length 1 cm, measuring temperature 23xc2x0 C.) of a 1 g/kg tetrahydrofuran solution of the CPVC according to Invention I-13 is not more than 0.8 at the wavelength 235 nm. For the CPVC according to Invention I-13, the absorbance value is used for quantitating exotic structures in the molecular chain resulting from the chlorination reaction and is used as an indicator of heat stability. The absorbance is determined by measuring the ultraviolet absorption spectrum and reading the absorbance value at the wavelength 235 nm (cell length 1 cm, measuring temperature 23xc2x0 C.) at which radiant energy is absorbed by the exotic structures xe2x80x94CHxe2x95x90CHxe2x80x94C(xe2x95x90O)xe2x80x94 and xe2x80x94CHxe2x95x90CHxe2x80x94CHxe2x95x90CHxe2x80x94 occurring in the CPVC. The reason why the absorbance should be not more than 0.8 is as follows. The chlorine atom bound to the carbon atom adjacent to the double bond is unstable and hydrogen chloride elimination occurs from that site, Thus, with the increase in absorbance value, the hydrogen chloride elimination becomes more and more ready to occur, hence the heat stability decreases. When the absorbance value exceeds 0.8, the influence of the exotic structures in the molecular chain increases, with the result that the heat stability becomes poor. A preferred value is not more than 0.2.
The method of chlorination by which the above-defined absorbance of the 1 g/kg tetrahydrofuran solution can be maintained at 0 to 0.8 is not particularly restricted but includes the thermal chlorination and photochlorination techniques, preferably the high temperature chlorination technique. The high heat stability obtainable by carrying out the reaction at a high temperature is attributable to the fact that the oxidation (formation of exotic structures, typically the carbonyl group) during the chlorination reaction becomes difficult to occur as the temperature rises (as the temperature rises, the reaction equilibrium shifts in the direction to suppression of their formation). Specifically, the reaction is carried out at a temperature within the range of 70 to 135xc2x0 C., more preferably within the range of 90 to 125xc2x0 C. At a reaction temperature lower than 70xc2x0 C., the rate of the chlorination reaction is low and it becomes necessary to add a large amount of a reaction catalyst, typically a peroxide, for causing the reaction to proceed. As a result, the resin obtained is inferior in heat stability. In the case of photochlorination, when the reaction temperature is lower than 70xc2x0 C., chlorine is readily soluble in water and oxygen is readily generated in the reaction vessel. As a result, the resin obtained shows inferior heat stability. At a reaction temperature exceeding 135xc2x0 C., the resin is deteriorated by thermal energy and the CPVC obtained shows discoloration.
The CPVC according to Invention I-14 is defined by a chlorine content, a void ratio, a BET specific surface area and an absorbance at 235 nm, each specified.
The chlorine content, void ratio and BET specific surface area are the same as those according to Invention I-2, and the absorbance at 235 nm is the same as that according to Invention I-13.
The CPVC according to Invention I-15 is defined by a chlorine content, a void ratio, a void volume for 0.001 to 0.1 xcexcm and an absorbance at 235 nm, each specified.
The chlorine content, void ratio and void volume for 0.001 to 0.1 xcexcm are the same as those according to Invention I-13.
The absorbance at 235 nm of the CPVC according to Invention I-15 is not more than 0.2. When the absorbance at 235 nm is not more than 0.2, the CPVC shows particularly good heat stability.
The CPVC according to Invention I-16 is defined by a chlorine content, a void ratio, a BET specific surface area and an absorbance at 235 nm, each specified.
The chlorine content, void ratio and BET specific surface area are the same as those according to Invention I-14, and the absorbance at 235 nm is the same as that according to Invention I-15.
The CPVCs according to Invention I-11 to Invention I-18 can be produced, for example, by using the method of producing a chlorinated vinyl chloride resin according to the invention (Invention I-19 to Invention 1-21).
The CPVCs according to Invention I-17 and Invention I-18 satisfy the following relations (1) and (2):
xe2x88x923.9X+305xe2x89xa7Yxe2x89xa7xe2x88x923.9X+300xe2x80x83xe2x80x83(1)
xe2x88x923.2X+270xe2x89xa7Zxe2x89xa7xe2x88x923.2X+265xe2x80x83xe2x80x83(2)
wherein X is the chlorine content (% by weight) of the chlorinated vinyl chloride resin, Y is the amount (g) of methyl alcohol required for initiating precipitation of the chlorinated vinyl chloride resin when 3.0 g of the resin is completely dissolved in 60 g of tetrahydrofuran at 20xc2x0 C. and then methyl alcohol is gradually added to the solution to thereby cause precipitation of the resin, and Z is the amount (g) of methyl alcohol required to cause 80% by weight of the resin to precipitate.
With the addition of methyl alcohol after complete dissolution of the CPVC in tetrahydrofuran, that fraction of the chlorinated vinyl chloride resin dissolved which is high in chlorination percentage begins to precipitate out. The above-defined Y (amount of methyl alcohol required for initiating precipitation of the chlorinated vinyl chloride resin) is an indicator showing the occurrence of a high chlorination percentage resin fraction, and Z (amount of methyl alcohol required to cause 80% by weight of the chlorinated vinyl chloride resin to precipitate) is an indicator showing the occurrence of a low chlorination percentage resin fraction. The CPVC satisfying the above relations (1) and (2) is narrow in chlorination degree distribution (uniformly chlorinated until the core of particles) and has high heat resistance.
As the method of chlorination for obtaining CPVCs satisfying the above relations (1) and (2), there may be mentioned the method comprising carrying out the heat chlorination reaction at a high temperature. The reason why uniform chlorination within particles can be attained by the high temperature reaction is that the rate of diffusion is a function of temperature and the diffusion of chlorine into the interior of particles readily occurs at elevated temperatures. Specifically, the chlorination reaction is carried out at a temperature within the range of 120 to 135xc2x0 C. At a reaction temperature below 120xc2x0 C., the diffusion of chlorine into the interior of particles is not sufficient, hence the above relations (1) and (2) cannot be satisfied. The chlorination degree distribution in the interior of particles is broad and, as a result, the resin obtained is inferior in heat stability. At a reaction temperature exceeding 135xc2x0 C., the resin is deteriorated by thermal energy and the resin obtained shows discoloration.
The PVC to be used in the method of producing a chlorinated vinvl chloride resin according to Invention I-19 is a resin produced by polymerizing VCM alone or a mixture of VCM and another monomer or other monomers copolymerizable with VCM by a method known in the art. The other monomers copolymerizable with VCM are not particularly restricted but include, for example, alkyl vinyl esters such as vinyl acetate; xcex1-monoolefins such as ethylene and propylene; vinylidene chloride; styrene; and the like. These may be used singly or two or more of them may be used combinedly.
The average degree of polymerization of the above PVC is not particularly restricted but may be 400 to 3,000, which is conventionally employed.
The PVC to be used in the practice of Invention I-19 has a BET specific surface area of 1.3 to 8 m2/g. When the specific surface area is smaller than 1.3 m2/g, the proportion of micropores not larger than 0.1 xcexcm in the interior of PVC particles becomes small, so that uniform chlorination cannot be attained and the heat stability will not be improved. Further, the rate of gelation is slow and this is undesirable from the molding viewpoint. When the specific surface area is greater than 8 m2/g, the heat stability of prechlorination PVC particles themselves is low and the CPVC obtained is poor in workability. A preferred range is 1.5 to 5 m2/g.
For the above PVC, the carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peakxc3x972/carbon element peak) as found by particle surface analysis by ESCA (electron spectroscopy for chemical analysis) should be above 0.6. When it is not more than 0.6, an additive, such as a dispersant, presumably remain adsorbed on the surface of PVC particles and, therefore, not only the rate of chlorination in the succeeding step becomes slow but also the CPVC obtained raises a moldability/fabricability problem and further has inferior heat stability. A peak ratio exceeding 0.7 is preferred.
Among PVCs for which the above, peak ratio is above 0.6, there are skinless PVCs whose skin area on the surface of PVC particles is small. When the energy ratio is the same, the use of a skinless PVC is preferred.
The element occurrence ratio in the chemical structure of the above PVC resin is chlorine element:carbon element=1:2 (without considering the terminal structure and branching) and the above-mentioned peak ratio (chlorine element peakxc3x972/carbon element peak) at the 1S bond energy value (eV) has a value of 0 to 1. The peak ratio value of 0 means that the surface of PVC particles is covered with some chlorine-free substance other than PVC, while the peak ratio value of 1 means that the surface of PVC resin particles is wholly covered with vinyl chloride components alone.
Those PVCs having the above-specified BET specific surface area and 1S bond energy value (eV) peak ratio can be obtained, for example, by aqueous suspension polymerization using a high saponification degree (60 to 90 mole percent) or low saponification degree (20 to 60 mole percent) polyvinyl acetate or both, a higher fatty acid ester or the like as the dispersant and an anionic emulsifier, a nonionic emulsifier or the like as the emulsifier.
The polymerizer (pressure-resistantautoclave) which can be used in producing the above PVC according to Invention I-19 by polymerization is not particularly restricted in shape and structure but may be any of those conventionally used in PVC polymerization, for instance. The agitating blades are not particularly restricted but include those in general use, such as Pfaudler blades, paddle blades, turbine blades, fan turbine blades and bull margin blades, among others. Pfaudler blades are judiciously used, however, and the combined use of baffle plates is not particularly restricted.
In chlorinating the above PVC, the PVC is suspended in an aqueous medium and liquid chlorine or gaseous chlorine is introduced into the reactor. The chlorination reaction is carried out at, a temperature within the range of 70 to 135xc2x0 C.
The chlorination reactor to be used in the practice of Invention I-19 may be a glass-lined stainless steel reactor or any of those in common use, for example a titanium reactor.
In the practice of Invention I-19, the chlorination is effected by suspending the PVC in an aqueous medium and introducing liquid or gaseous chlorine thereinto, namely by feeding a chlorine source into the chlorination reactor. From the process viewpoint, the introduction of liquid chlorine is efficient. As regards the chlorine supplement during reaction for adjusting the pressure or with the progress of the chlorination reaction, it is also possible to feed an adequate amount of gaseous chlorine by blowing, if necessary together with liquid chlorine.
The method of preparing the above suspended PVC is not particularly restricted but a cake-form post polymerization PVC after monomer removal treatment may be used or a PVC once dried may be again suspended in an aqueous medium, or a suspension resulting from removal of substances unfavorable to the chlorination reaction from the polymerization system may be used. It is preferable, however, to use the cake-like postpolymerization PVC after monomer removal treatment.
The amount of the aqueous medium to be charged into the reactor is not particularly restricted but, generally, the medium is charged in an amount of 2 to 10 times (by weight) the weight of PVC.
The method of effecting the chlorination in the above suspended state is not particularly restricted but, for example, mention may be made of the method comprising exciting resin bonds or chlorine by heating for promoting the chlorination (hereinafter referred to as xe2x80x9cthermal chlorinationxe2x80x9d) and the method comprising photochemically promoting the chlorination by irradiation with light (hereinafter-referred to as xe2x80x9cphoto-chlorinationxe2x80x9d), among others.
The method of heating for thermal chlorination is not particularly restricted but mention may be made, for example, of external jacket heating through the reactor wall, interior jacket heating and blowing steam into the reactor. Generally, the external jacket system or interior jacket system is effective. It is also possible to combined use thermal energy and light energy such as ultraviolet rays. In that case, however, an apparatus capable of ultraviolet irradiation under high-temperature and high-pressure conditions is required.
As regards the source of light for photo-chlorination, ultraviolet rays as well as visible light from a mercury lamp, arc lamp, candescent lamp, fluorescent lamp or carbon arc lamp or the like are suited for use and, in particular, ultraviolet rays are effective.
In the above chlorination process, the chlorine content of the product CPVC is preferably adjusted to 60 to 72% by weight, more preferably 63 to 70% by weight.
At a chlorine content less than 60% by weight, the heat resistance is poor and, at higher than 72% by weight, the gelation properties are inferior and this is disadvantageous in producing heat-resistant moldings.
The temperature for the above chlorination reaction is 70 to 135xc2x0 C., preferably 90 to 125xc2x0 C. At a reaction temperature below 70xc2x0 C., the rate of the chlorination reaction is slow, hence it is necessary to add a large amount of a reaction catalyst, typically a peroxide, for causing the reaction to proceed. As a result, the resin obtained is inferior in heat stability. At a reaction temperature above 135xc2x0 C., the resin is deteriorated by thermal energy and a discolored CPVC is obtained.
The chlorine to be used in the practice of the invention is not particularly restricted but, as described in Japanese Kokai Publication Hei-06-32822, the chlorine remaining after purging of 5 to 10% by weight of the cylinder chlorine is preferably used.
The gauge-pressure in the above reactor is not particularly restricted but, since a higher chlorine pressure causes ready penetration of chlorine into the interior of PVC particles, a pressure within the range of 0.3 to 2 MPa is preferred.
The CPVC according to the invention is first characterized by the structure of CPVC particles. Namely, by defining the interior porous state, a ready gelation tendency in the step of molding is secured. In the next place, by defining the exotic structure content in the CPVC molecular chain, high heat stability is secured. In this way, a resin having both high heat stability and ready gelation tendency is provided by the present invention.
In the production method of the invention, in the first place, the particle structure of the PVC has a characteristic feature. Namely, by defining the surface condition and interior porous state, a ready gelation tendency in the step of molding is developed. In the next place, by carrying out the high-temperature chlorination at a specified reaction temperature, high heat stability is developed. This high heat stability development by that high-temperature reaction is due to the fact that the oxidation (formation of exotic structures, typically the carbonyl group) hardly occurs at elevated temperatures (the reaction equilibrium shifts to the direction to suppression of the formation of such structures as the temperature rises). Thus, it becomes possible according to the invention to produce a resin having both high heat stability and ability to form a gel readily.
Then, the second aspect of the invention is described in detail.
The chlorinated vinyl chloride resin of the invention is a chlorinated vinyl chloride resin obtained by chlorinating a vinyl chloride resin and has a chlorine content of 72 to 76% by weight, a void ratio of 30 to 40% by volume as determined by mercury porosimetry at the pressure 2,000 kg/cm2 and a volume percentage of voids 0.001 to 0.1 xcexcm in size of 2 to 15% by volume relative to the total void volume in the pore volume distribution determined by mercury porosimetry in the pressure range of 0 to 2,000 kg/cm2.
The CPVC of the invention is obtained by chlorinating a resin produced by polymerizing monomeric vinyl chloride (hereinafter referred to as xe2x80x9cVCMxe2x80x9d) alone or a mixture of VCM and another monomer or other monomers copolymerizable with VCM by a method known in the art. The other monomers copolymerizable with VCM are not particularly restricted but include, for example, alkyl vinyl esters such as vinyl acetate; xcex1-monoolefins such as ethylene and propylene; vinylidene chloride; styrene; and the like. These may be used singly or two or more may be used combinedly.
The CPVC of the invention has a chlorine content of 72 to 76% by weight. When the chlorine content is less than 72% by weight, it is difficult to fully attain the intended improvement in heat resistance, which should amount to 65 to 80xc2x0 C. in terms of Vicat softening temperature, for instance, hence it becomes difficult to use the CPVC in those fields where higher heat resistance is required as compared with the group of currently available heat resistant products. When the chlorine content is higher than 76% by weight, molding becomes difficult and gelation becomes insufficient. Further, a higher amount of catalyst addition is required for increasing the reactivity and, as a result, the heat stability decreases. For attaining a balance between quality and productivity in commercial production, the upper limit to the chlorine content is 76% by weight. A preferred chlorine content is within the range of 72 to 74% by weight.
The CPVC of the invention has a void ratio of 30 to 40% by volume. The void ratio is determined by mercury porosimetry at the pressure 2,000 kg/cm2. When the void ratio is less than 30% by volume, the gelation in the step of molding is slow and this is unfavorable to molding. When it is above 40% by volume, the biting by the screws in the step of molding becomes worse and the gelation properties are inferior. It is preferably 31 to 38% by volume.
The CPVC of the invention has a volume percentage of voids 0.001 to 0.1 xcexcm in size of 2 to 15% by volume relative to the total void volume in the pore volume distribution determined by mercury porosimetry in the pressure range of 0 to.2,000 kg/cm2. The void pore diameter in the interior of resin particles is a function of the pressure of mercury filled into void pores of the resin and, therefore, the pore size distribution can be determined by continuously measuring the mercury filling pressure and mercury weight. When the void volume for the range 0.001 to 0.1 xcexcm is less than 2% by volume relative to the total void volume, the proportion of micropores in the interior of particles is insufficient and the gelation property in the step of molding is inferior. When it is above 15% by volume, the diffusion of chlorine in the step of chlorination is not effected in a balanced manner but the chlorination degree distribution in the interior of particles becomes excessive, giving no good heat stability. The void volume for the range 0.001 to 0.1 xcexcm preferably amounts to 3 to 13% by volume of the total void volume.
The chlorinated vinyl chloride resin according to Invention II-2 is a chlorinated vinyl chloride resin obtained by chlorinating a vinyl chloride resin and has a chlorine content of 72 to 76% by volume, a void ratio of 30 to 40% by volume as determined by mercury porosimetry at the pressure 2,000 kg cm2 and a BET specific surface area of 2 to 12 m2/g.
The CPVC according to Invention II-2 has a BET specific surface area of 2 to 12 m2/g. When the BET specific surface area is smaller than 2 m2/g, the proportion of micropores in the interior of particles is insufficient and, in the step of molding, intraparticle melting becomes difficult to occur, resulting in inferior gelation property. When the BET specific surface area is larger than 12 m2/g, the heat stability in the step of molding becomes poor due to abrupt frictional heat generation from the inside. A preferred BET specific surface area is 3 to 10 m2/g.
The chlorinated vinyl chloride resin according to Invention II-3 is a CPVC according to Invention II-1 or Invention II-2 which, in particle surface analysis by ESCA (electron spectroscopy for chemical analysis), shows a carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peak/carbon element peak) of higher than 0.6 When the above peak ratio is not higher than 0.6, it is probable that an additive, such as a dispersant, remain adsorbed-on the surface of CPVC particles. This is unfavorable to molding/fabrication. The ratio is more preferably higher than 0.7.
Among CPVCs for which the above peak ratio is above 0.6, there are skinless CPVCs having a small skin area on the surface of CPVC particles.
When the chlorine content is 72% by weight, the element occurrence ratio for the chemical structure of the above CPVC is chlorine element:carbon element =1.89:2 (without considering terminal structures or branching) and, when the peak ratio at the above 1S bond energy value (eV) is 0.945, this means that the surface of CPVC particles is wholly covered with chlorinated vinyl chloride components alone.
CPVCs having the above-specified void ratio, pore distribution, BET specific surface area and 1S bond energy (eV) peak ratio are obtained by chlorinating a PVC produced by aqueous suspension polymerization using a high saponification degree (60 to 90 mole percent) or low saponification degree (20 to 60 mole percent) polyvinyl acetate or both, a higher fatty acid ester or the like as the dispersant and an anionic emulsifier, a nonionic emulsifier or the like as the emulsifier.
The method of producing the CPVC of the invention is not particularly restricted provided that a CPVC having the above-specified properties can be obtained. For example, mention may be made of the method according to the invention for producing chlorinated vinyl chloride resins, as mentioned below.
The method according to Invention II-4 for producing chlorinated vinyl chloride resins is a method of producing a chlorinated vinyl chloride resin by chlorinating a vinyl chloride resin wherein said vinyl chloride resin has a BET specific surface area of 1.3 to 8 m2/g and a carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peakxc3x972/carbon element peak) of higher than 0.6 as found by particle surface analysis by ESCA (electron spectroscopy for chemical analysis) and the chlorination reaction is carried out by introducing liquid-chlorine or gaseous chlorine into the reactor where the above vinyl chloride resin occurs in a state suspended in an aqueous medium and. effecting the chlorination at a temperature within the range of 70 to 135xc2x0 C. until a chlorine content of 72 to 76% by weight is attained.
The PVC to be used in carrying out the production method according to Invention II-4 is are in produced by polymerizing, by a method known in the art, VCM alone or a mixture of VCM and another monomer or other monomers copolymerizable with VCM. The other monomers copolymerizable with VCM are not particularly restricted but include, for example, alkyl vinyl esters such as vinyl acetate; xcex1-monoolefins such as ethylene and propylene; vinylidene chloride; styrene; and the like. These may be used singly or two or more of them may be used combinedly.
The average molecular weight of the above PVC is not particularly restricted but may be 400 to 3,000, as is conventional in the art.
The PVC to be used in the practice of Invention II-4 has a BET specific surface area of 1.3 to 8 m2/g. When the specific surface area is smaller than 1.3 m2/g, the proportion of micropores not larger than 0.1 xcexcm in the interior of PVC particles becomes small, so that uniform chlorination cannot be attained and the heat stability will not be improved. Further, the rate of gelation is slow and this is undesirable from the molding viewpoint. When the specific surface area is greater than 8 m2/g, the heat stability of prechlorination PVC particles themselves is low and the CPVC obtained is poor in workability. A preferred range is 1.5 to 5 m2/g.
For the above PVC, the carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peakxc3x972/carbon element peak) as found by particle surface analysis by ESCA (electron spectroscopy for chemical analysis) should be above 0.6. When it is not more than 0.6, an additive, such as a dispersant, presumably remain adsorbed on the surface of PVC particles and, therefore, not only the rate of chlorination in the succeeding step becomes slow but also the CPVC obtained raises a moldability/fabricability problem and further has inferior heat stability. A peak ratio exceeding 0.7 is preferred.
Among PVCs for which the above peak ratio is above 0.6, there are skinless PVCs whose skin area on the surface of PVC particles is small. When the energy ratio is the same, the use of a skinless PVC is preferred.
The element occurrence ratio in the chemical structure of the above PVC resin is chlorine element:carbon element=1:2 (without considering the terminal structure and branching) and the above-mentioned peak ratio (chlorine element peakxc3x972/carbon element peak) at the 1S bond energy value (eV) has a value of 0 to 1. As already discussed referring to the first aspect of the invention, the peak ratio value of 0 means that the surface of PVC particles is covered with some chlorine-free substance other than PVC, while the peak ratio value of 1 means that the surface of PVC resin particles is wholly covered with vinyl chloride components alone.
Those PVCs having the above-mentioned BET specific surface area and 1S bond energy value (eV) peak ratio can be obtained, for example, by aqueous suspension polymerization using a high saponification degree (60 to 90 mole percent) or low saponification degree (20 to 60 mole percent) polyvinyl acetate or both, a higher fatty acid ester or the like as the dispersant and an anionic emulsifier, a nonionic emulsifier or the like as the emulsifier.
The polymerizer (pressure-resistant autoclave) which can be used in producing the above PVC according to Invention II-4 by polymerization is not particularly restricted in shape and structure but may be any of those described hereinabove referring to the first aspect of the invention.
In chlorinating the above PVC, the PVC is suspended in an aqueous medium and liquid chlorine or gaseous chlorine is introduced into the reactor. The chlorination reaction is carried out at a temperature within the range of 70 to 135xc2x0 C. until the chlorine content of the resulting CPVC arrives at 72 to 76% by weight.
The chlorination reactor to be used in the practice of Invention II-4 is not particularly restricted in material but may be a glass-lined stainless steel reactor or any of those in common use, for example a titanium reactor.
In carrying out the chlorination according to Invention II-4, the PVC is suspended in an aqueous medium and liquid chlorine or gaseous chlorine is introduced thereinto, namely a chlorine source is fed to the chlorination reactor. From the process viewpoint, the introduction of liquid chlorine is efficient. As regards the chlorine supplement during reaction for adjusting the pressure or with the progress of the chlorination reaction, it is also possible to feed an adequate amount of gaseous chlorine by blowing, if necessary, together with liquid chlorine.
In the practice of Invention II-4, the method of preparing the PVC suspended in an aqueous medium is not particularly restricted but a cake-form postpolymerization PVC after monomer removal treatment may be used or a PVC once dried may be again suspended in an aqueous medium, or a suspension resulting from removal of substances undesirable for the chlorination reaction from the polymerization system may be used. It is preferable, however, to use the cake-like postpolymerization PVC after monomer removal treatment.
The amount of the aqueous medium to be charged into the reactor is not particularly restricted but, preferably, the medium is charged in an amount of 2 to 10 times (by weight) the weight of PVC.
In the practice of Invention II-4, the method of effecting the chlorination in the above suspended state is not particularly restricted but, for example, mention may be made of thermal chlorination and photo-chlorination, among others. Thermal chlorination is preferably employed, however.
In the above process of chlorination, the chlorine content of the resulting CPVC is adjusted to 72 to 76%, preferably 72 to 74% by weight. When the chlorine content is less than 72% by weight, it is difficult to fully attain the intended improvement in heat resistance, which should amount to 65 to 80xc2x0 C. in terms of Vicat softening temperature, for instance, hence it becomes difficult to use the CPVC in those fields where higher heat resistance is required as compared with the group of currently available heat resistant products. When the chlorine content is higher than 76% by weight, molding becomes difficult and gelation becomes insufficient. Further, a higher amount of catalyst addition is required for increasing the reactivity and, as a result, the heat stability decreases. For attaining a balance between quality and productivity in commercial production, the upper limit to the chlorine content is 76% by weight. A preferred chlorine content is within the range of 72 to 74% by weight.
In the practice of Invention II-4, the temperature for the above chlorination reaction is 70 to 135xc2x0 C., preferably 90 to 125xc2x0 C. At a reaction temperature below 70xc2x0 C., the rate of the chlorination reaction is slow, hence a long period of time is required for the reaction. Further, forcausing the reaction to proceed without light irradiation, it is necessary to add a large amount of a reaction catalyst, typically a peroxide and, as a result, the resin obtained is inferior in heat stability. At a reaction temperature above 135SC, the resin is deteriorated by thermal energy and a product CPVC is discolored.
The CPVC of the invention is characterized by its particle structure. While it is generally difficult to mold a CPVC having a chlorine content of 72% by weight or higher, it is possible according to the present invention to realize ready gelation tendency in the step of molding by causing CPVC particles to have a specific interior porous state and a specific particle surface state. In this way, a resin having both high heat resistance and ready gelation tendency is provided by the present invention.
In the production method of the invention, in the first place, the particle structure of the PVC has a characteristic feature. Namely, by providing a specific surface condition and interior porous state, the ready gelation tendency in the step of molding is increased. In the next place, the PVC chlorination is carried out at a specific high temperature and to a specified degree of chlorination. While molding generally becomes difficult at a chlorine content of 72% by weight or higher, it is possible according to Invention II-4 to attain ready gelation tendency in the step of molding by combining a structurally characterized PVC and a specific method of chlorination. Thus, it becomes possible according to the invention II-4 to produce a resin having both high heat resistance and ready gelation tendency.
Then, the third aspect of the invention is described in detail.
The CPVC pipe, CPVC joint and CPVC plate according to the present invention is characterized by having a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The CPVC pipe according to Invention III-1 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The Vicat softening temperature is an indicator of the heat resistance of pipes. Pipes having a Vicat softening temperature lower than 145xc2x0 C. can hardly be used in the case that a liquid or gas having a temperature of 100xc2x0 C. or above is passed therethrough and therefore a higher level of heat resistance is required as compared with the fields in which the prior art products are used, typically in the field of hot water supply pipes.
The upper limit to the above Vicat softening temperature is desirably as high as possible. Considering the actual molding extrusion technology for pipes, however, the limit is at 185xc2x0 C.
The above CPVC preferably has a chlorine content of 70 to 76% by weight. A chlorine content lower than 70% by weight is insufficient for increasing the heat resistance, namely the above-mentioned Vicat softening temperature at a load of 1 kgf, to a level not lower than 145xc2x0 C. and, therefore, the resulting products can hardly be used in those fields where still higher heat resistance is required as compared with the currently available heat-resistant product groups. At a content exceeding 76% by weight, the molding is difficult and the gelation is insufficient.
The above CPVC pipe is sufficient in gelation and has excellently developed shock resistance and other physical properties in spite of the use of a high chlorine content CPVC. The improvement in ready gelation tendency owes to the characteristic interior porous condition and surface condition of CPVC particles. Namely, the particle structure of the CPVC particles is characterized by a void ratio of 30 to 40% by volume as determined by mercury porosimetry at the pressure 2,000 kg/cm2. A more preferred void ratio is within the range of 31 to 38% by volume. When the void volume is less than 30% by volume, the gelation in the step of molding is slow and this is unfavorable for the molding. When it is above 40% by volume, the biting by the screws in the step of molding becomes poor and the gelation tendency is inferior.
The above CPVC has a void volume percentage for the range of 0.001 to 0.1 xcexcm of 2 to 15% by volume, preferably 3 to 13% by volume, relative to the total void volume in the pore volume distribution determined by the same measurement method as in the void ratio measurement in the pressure range of 0 to 2,000 kg/cm2. When the void volume for the range of 0.001 to 0.1 xcexcm, the proportion of micropores in the interior of particles is insufficient and the gelation tendency in the step of molding is poor. When it is above 15% by volume, the diffusion of chlorine in the step of chlorination will not be effected in a balanced manner but the chlorination degree distribution in the interior of particles becomes excessive, hence the heat stability is poor.
The above CPVC further has a BET specific surface area within the range of 2 to 12 m2/g, more preferably 3 to 10 M2/g. When it is smaller than 2 m2/g, the proportion of micropores in the interior of particles is insufficient, hence intraparticle melting hardly occurs in the step of molding and, thus, the gelation tendency becomes poor. When it is larger than 12 m2/g, frictional heat generation from the inside occurs abruptly and the heat stability in the step of molding becomes inferior.
Further, the above CPVC preferably has a peak ratio (chlorine element peak/carbon element peak) exceeding 0.6, more preferably exceeding 0.65, at the carbon element-chlorine element 1S bond energy value (eV) as determined by particle surface analysis by ESCA (electron spectroscopy for chemical analysis). When the above peak ratio is smaller, it is presumed that an additive, for example a dispersant, are adsorbed on the surface of CPVC particles. This is undesirable from the molding viewpoint.
Among CPVCs for which the above peak ratio is above 0.6, there are skinless CPVCs having a small skin area on the surface of CPVC particles.
When the chlorine content is 70% by weight, the element occurrence ratio for the chemical structure of the above CPVC is chlorine element: carbon element =1.73:2 without considering terminal structures or branching and, when the peak ratio at the above 1S bond energy value (eV) is 0.865, this means that the surface of CPVC particles is wholly covered with chlorinated vinyl chloride components alone.
CPVCs having the above-specified void ratio, pore distribution, BET specific surface area and ESCA analysis value are obtained by chlorinating a resin produced by polymerizing VCM alone or a mixture of VCM and another monomer or other monomers copolymerizable with VCM by a method known in the art.
The other monomers copolymerizable with VCM are not particularly restricted but include, for example, alkyl vinyl esters such as vinyl acetate; xcex1-monoolefins such as ethylene and propylene; vinylidene chloride; styrene; and the like. These may be used singly or two or more of them may be used combinedly.
The CPVC having the above-specified BET specific surface area and 1S bond energy (eV) peak ratio can be obtained, for example, by aqueous suspension polymerization using a high saponification degree (60 to 90 mole percent) or low saponification degree (20 to 60 mole percent) polyvinyl acetate or both, a higher fatty acid ester or the like as the dispersant and a nonionic emulsifier, an anionic emulsifier or the like as the emulsifier.
The above chlorination is effected by introducing liquid chlorine or gaseous chlorine into a reactor in which PVC occurs in a state suspended in an aqueous medium.
In preparing the above suspended resin, the cake-like resin after monomer removing treatment following PVC polymerization is preferably used. A PVC once dried may be again suspended in an aqueous medium. Further, the suspension obtained after removal of substances unfavorable to the chlorination reaction from the polymerization system may also be used.
In chlorinating the above suspension, the reaction is carried out in the manner of thermal chlorination. The method of heating for the thermal chlorination is the same as described referring to the first aspect and second aspect of the invention.
The above reaction is carried out at a reaction temperature within the range of 70 to 135xc2x0 C., more preferably 85 to 120xc2x0 C. At a reaction temperature below 70xc2x0 C., the rate of chlorination reaction is low and, accordingly, a long period of time is required for the reaction. At a temperature above 135xc2x0 C., the decrease in voids in the interior of particles becomes significant through the influence of thermal energy owing to the high temperature reaction, so that sufficient gelation cannot be attained in the step of molding/fabrication. Further, the resin is deteriorated by the thermal energy.
In molding the above CPVC pipe, the molding can be effected using conventional compounding additives, such as a stabilizer, lubricant, modifier, filler, processing aid, pigment, etc.
The molding machine to be used in the above CPVC pipe molding is not particularly restricted but includes, among others, a single-screw extruder, twin-screw two-directional parallel extruder, twin-screw two-directional conical extruder and twin-screw unidirectional extruder.
The mold, resin temperature and molding conditions for molding the above CPVC pipe are not particularly restricted.
The gist of this invention consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 145xc2x0 C.
The CPVC pipe according to Invention III-2 has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
When the above Vicat softening temperature is 155xc2x0 C. or higher, the pipe can be used in a steam return piping system, for instance.
The CPVC to be used in producing the CPVC pipe according to Invention III-2 preferably has a chlorine content of 72 to 76% by weight. A chlorine content lower than 72% by weight is insufficient to attain heat resistance, namely raising the above Vicat softening temperature to l55xc2x0 C. or above, hence the pipe cannot be used in a steam return piping system. When the chlorine content is above 76% by weight, the molding is difficult to conduct and the gelation is insufficient.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-2 is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-2, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-1. Since, however, the chlorine content of the CPVC to be used in producing the CPVC pipe according to Invention III-2 is nigher than that of the CPVC to be used in producing the CPVC pipe according to Invention III-1, a more preferred reaction temperature is within the range of 90 to 120xc2x0 C.
The CPVC pipe according to Invention III-2, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-2 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure, and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 155xc2x0 C.
The CPVC pipe according to Invention III-3 has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The CPVC to be used in producing the CPVC pipe according to Invention III-3 preferably has a chlorine content of 74 to 76% by weight. A chlorine content lower than 74% by weight is insufficient to increase the heat resistance, namely the above-mentioned Vicat softening temperature at a load of 1 kgf, to a level not lower than 170xc2x0 C. and, therefore, the resulting products can hardly be used in those fields where still higher heat resistance is required as compared with the currently available heat-resistant product groups. At a content exceeding 76% by weight, the molding is difficult and the gelation is insufficient.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-3 is also characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-3 can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-I or Invention III-2. Since, however, the chlorine content of the CPVC to be used in producing the CPVC pipe according to Invention III-3 is higher than that of the CPVC to be used in producing the CPVC pipe according to Invention III-1 or Invention III-2, a more preferred reaction temperature is within the range of 100 to 120xc2x0 C.
The CPVC pipe according to Invention III-3, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-3 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 170xc2x0 C.
The CPVC pipe according to Invention III-4 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The above Charpy impact strength is an indicator of the shock resistance of a pipe and, when the Charpy impact strength is not less than 10 kgfxc2x7cm/cm2, the pipe is suited for use for passing a liquid or gas at 100xc2x0 C. or above therethrough.
The CPVC pipe according to Invention III-4 is molded using a CPVC having an increased chlorine content so that the heat resistance may be increased. However, the use of a highly chlorinated resin results in insufficient gelation in the step of molding and thus gives a brittle pipe with decreased shock resistance. Therefore, an increased amount of a shock resistance improving agent is used in the step of molding but, on the other hand, the use of such agent may decrease the heat resistance. A preferred range is, therefore, 10 to 60 kgfxc2x7cm/cm2, more preferably 15 to 50 kgfxc2x7cm/cm2.
The CPVC to be used in producing the CPVC pipe according to Invention III-4 preferably has a chlorine content of 70 to 76%, like the CPVC according to Invention III-1.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-4, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-4, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-1.
The CPVC pipe according to Invention III-4, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-4 consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 145xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
Invention III-5 provides the CPVC pipe which has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
In the practice of Invention III-5, the CPVC preferably has a chlorine content of 72 to 76% by weight, like the CPVC according to Invention III-2.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-5, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-5, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-2.
The CPVC pipe according to Invention III-5, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-5 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 155xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The CPVC pipe according to Invention III-6 has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not Less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The chlorine content of the CPVC to be used in producing the CPVC pipe according to Invention III-6 is preferably 74 to 76% by weight, like the CPVC according to Invention III-3.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-6, too, is characterized by its particle inside structure and surface. structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-6, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-3.
The CPVC pipe according to Invention III-6, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-6 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific particle surface structure, and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 170xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The CPVC pipe according to Invention III-7 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The above Charpy impact strength is an indicator of the shock resistance of a pipe and, when the Charpy impact strength is not less than 20 kgfxc2x7cm/cm2, the pipe is particularly suited for use for passing a liquid or gas at 100xc2x0 C. or above therethrough.
The CPVC to be used in producing the CPVC pipe according to Invention III-7 preferably has a chlorine content of 70 to 76% by weight, like the CPVC according to Invention III-1 and Invention III-4.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-7, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-7, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-1 and Invention III-4.
The CPVC pipe according to Invention III-7, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-7 consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 145SC and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2.
The CPVC pipe according to Invention III-8 has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The chlorine content of the CPVC to be used in producing the CPVC pipe according to Invention III-8 is preferably 72 to 76% by weight, like the CPVC according to Invention III-2 and Invention III-5.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-8, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-8, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-2 and Invention III-5.
The CPVC pipe according to Invention III-8, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-8 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 155xc2x0 C. and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2.
The CPVC pipe according to Invention 111-9 has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The CPVC according to Invention III-9 preferably has a chlorine content of 74 to 76% by weight, like the CPVC according to Invention III-3 and Invention III-6.
The particle structure of the CPVC to be used in producing the pipe according to Invention III-9, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-9, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-3 and Invention III-6.
The CPVC pipe according to Invention III-9, too, can be molded in the same manner using the same compounding additives as mentioned above referring to the above-mentioned CPVC pipe of the invention.
The gist of Invention III-9 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC pipe having a Vicat softening temperature of not lower than 170xc2x0 C. and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2.
The CPVC joint according to Invention III-10 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The Vicat softening temperature is an indicator of the heat resistance of joints. Joints having a Vicat softening temperature lower than 145xc2x0 C. can hardly be used in those fields of application where a liquid or gas having a temperature of 100xc2x0 C. or higher is passed therethrough and therefore a higher level of heat resistance is required as compared with the fields in which the prior art products are used, typically in the field of joints for hot water supply systems.
The chlorine content of the CPVC to be used according to Invention III-10 is preferably 70 to 76% by weight, like the CPVC according to Invention III-1, Invention III-4 and Invention III-7.
The particle structure of the CPVC to be used in producing the CPVC joint according to Invention III-10, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-10, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-1, Invention III-4 and Invention III-7.
In producing the CPVC joint according to Invention III-10, the same compounding additives as mentioned hereinabove referring to the above-mentioned CPVC pipe of the invention can be used.
The molding machine to be used in molding the CPVC joint according to Invention III-10 is not particularly restricted but the technique of injection molding is judiciously used as the method of molding.
The mold, resin temperature and molding conditions for producing the CPVC joint according to Invention III-10 are not particularly restricted, either.
The gist of Invention III-10 consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 145xc2x0 C.
The CPVC joint according to Invention III-11 has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The CPVC according to Invention III-11 preferably has a chlorine content of 72 to 76% by weight, like the CPVC according to Invention III-2, Invention III-5 and Invention III-8.
The particle structure of the CPVC to be used in producing the joint according to Invention III-11, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-11, too, can be obtained in the same manner as the CPVC to be used in the practice of Invention III-2, Invention III-5 and Invention III-8.
The CPVC joint according to Invention III-11 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the above-mentioned CPVC pipe and CPVC joint of the invention.
The gist of Invention III-11 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 155xc2x0 C.
The CPVC joint according to Invention III-12 has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The chlorine content of the CPVC to be used in the practice of Invention III-12 is preferably 74 to 76% by weight, like the CPVC to be used in the practice of Invention III-3, Invention III-6 and Invention III-9.
The particle structure of the CPVC to be used in producing the CPVC joint according to Invention III-12, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-12, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-3, Invention III-6 and Invention III-9.
The CPVC joint according to Invention III-12 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC joint of the invention.
The gist of Invention III-12 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 170xc2x0 C.
The CPVC joint according to Invention III-13 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The Charpy impact strength is an indicator of the shock resistance of a joint and, when the Charpy impact strength is not less than 10 kgfxc2x7cm/cm2, the joint is suited for use for passing a liquid or gas at 100xc2x0 C. or above therethrough.
The chlorine content of CPVC to be used in the practice of Invention III-13 is preferably 70 to 76% by-weight, like the CPVC to be used in the practice of Invention III-1, Invention III-4, Invention III-7 and Invention III-10.
The particle structure of the CPVC to be used in producing the CPVC joint according to Invention III-13, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-13, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-1, Invention III-4 and Invention III-7 and the CPVC joint according to Invention III-10.
The CPVC joint according to Invention III-13 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC joint of the invention.
The gist of Invention III-13 consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 145xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The CPVC joint according to Invention III-14 has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The chlorine content of the CPVC to be used in the practice of Invention III-14 is preferably 72 to 76% by weight, like the CPVC to be used in the practice of Invention III-2, Invention III-5, Invention III-8 and Invention III-11.
The particle structure of the CPVC to be used in producing the CPVC joint according to Invention III-14, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-14, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-2, Invention III-5 and Invention III-8 and the CPVC joint according to Invention III-11.
The CPVC joint according to Invention III-14 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC joint of the invention.
The gist of Invention III-14 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 155xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The CPVC joint according to Invention III-15has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgf cm/cm2 as determined by the method according to JIS K 7111.
The CPVC to be used in the practice of Invention III-15 preferably has a chlorine content of 74 to 76% by weight, like the CPVC to be used in the practice of Invention III-3, Invention III-6, Invention III-9 and Invention III-12.
The particle structure of the CPVC to be used in producing the CPVC joint according to Invention III-15, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-15, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention-III-3, Invention III-6 and Invention III-9 and the CPVC joint according to Invention III-12.
The CPVC joint according to Invention III-15 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC joint of the invention.
The gist of Invention III-15 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 170xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The CPVC joint according to Invention III-16 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The above Charpy impact strength is an indicator of the shock resistance of a joint and, when the Charpy impact strength is not less than 20 kgfxc2x7cm/cm2, the joint is particularly suited for use for passing a liquid or gas at 100xc2x0 C. or above therethrough.
The CPVC to be used in the practice of Invention III-16 preferably has a chlorine content of 70 to 76% by weight, like the CPVC to be used in the practice of Invention III-1, Invention III-4, Invention III-7, Invention III-10 and Invention III-13.
The particle structure of the CPVC to be used in producing the CPVC joint according to Invention III-16, too is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-16, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-1, Invention III-4 and Invention III-7 and the CPVC joint according to Invention III-10 and Invention III-13.
The CPVC joint according to Invention III-16 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC joint of the invention.
The gist of Invention III-16 consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 145xc2x0 C. and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2.
The CPVC joint according to Invention III-17 has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The CPVC to be used in the practice of Invention III-17 preferably has a chlorine content of 72 to 76%-by weight, like the CPVC to be used in the practice of Invention III-2, Invention III-5, Invention III-8, Invention III-11 and Invention III-14.
The particle structure of the CPVC to be used in producing the CPVC joint according to Invention III-17, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC pipe according to Invention III-17, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-2, Invention III-5 and Invention III-8 and the CPVC joint according to Invention III-11 and as Invention III-14.
The CPVC joint according to Invention I1I-17 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC joint of the invention.
The gist of Invention III-17 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 155xc2x0 C. and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2.
The CPVC joint according to Invention III-18 has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The CPVC to be used in the practice of Invention III-18 preferably has a chlorine content of 74 to 76% by weight, like the CPVC to be used in the practice of Invention III-3, Invention III-6, Invention III-9, Invention III-12 and Invention III-15.
The particle structure of the CPVC to be used in producing the CPVC pipe according to Invention III-18, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC joint according to Invention III-18, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe according to Invention III-3, Invention III-6 and Invention III-9 and the CPVC joint according to Invention III-12 and Invention III-15.
The CPVC joint according to Invention III-18 can be molded in the same manner as the above-mentioned CPVC joint of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC joint of the invention.
The gist of Invention III-18 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific-particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC joint having a Vicat softening temperature of not lower than 170xc2x0 C. and a Charpy impact strength of not less than 20 kgfxc2x7cm/cm2.
The CPVC plate according to Invention III-19 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The Vicat softening temperature is an indicator of the heat resistance of a resin plate. Plates having a Vicat softening temperature lower than 145xc2x0 C. can hardly be used in those fields of application where a liquid or gas having a temperature of 100xc2x0 C. or higher is allowed to flow and therefore a higher level of heat resistance is required as compared with the fields in which the prior art products are used, typically in the field of reservoirs for chemical fluids.
The CPVC plate according to Invention III-19 preferably has a chlorine content of 70 to 76% by weight, like the CPVC pipe or CPVC joint according to Invention III-1, Invention III-4, Invention III-7, Invention III-10, Invention III-13 and Invention III-16.
The particle structure of the CPVC to be used in producing the CPVC plate according to Invention III-19, too, is, characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe and CPVC joint of the invention.
The CPVC to be used in producing the CPVC plate according to Invention III-19, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe or CPVC joint according to Invention III-1, Invention III-4, Invention III-7, Invention III-10, Invention III-13 and Invention III-16.
In producing the CPVC plate according to Invention III-19, the same compounding additives as mentioned above referring to the CPVC pipe of the invention can be used.
The molding machine to be used in molding the CPVC plate according to Invention III-19 is not particularly restricted but the technique of injection molding is judiciously used as the method of molding.
The mold, resin temperature and molding conditions for producing the CPVC plate according to Invention III-19 are not particularly restricted, either.
The gist of Invention III-19 consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC plate having a Vicat softening temperature of not lower than 145xc2x0 C.
The CPVC plate according to Invention III-20 has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The CPVC plate according to Invention III-20 preferably has a chlorine content of 72 to 76% by weight, like the CPVC pipe or CPVC joint according to Invention III-2, Invention III-5, Invention III-8, Invention III-11, Invention III-14 and Invention III-17.
The particle structure of the CPVC to be used in producing the CPVC plate according to Invention III-20, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe, CPVC joint and CPVC plate of the invention.
The CPVC to be used in producing the CPVC plate according to Invention III-20, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe or CPVC joint according to Invention III-2, Invention III-5, Invention III-8, Invention III-11, Invention III-14 and Invention III-17.
The CPVC plate according to Invention III-20 can be molded in the same manner as the above-mentioned CPVC plate of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe, CPVC joint and CPVC plate of the invention.
The gist of Invention III-20 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC plate having a Vicat softening temperature of not lower than 155xc2x0 C.
The CPVC plate according to Invention III-21 has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206.
The CPVC plate according to Invention III-21 preferably has a chlorine content of 74 to 76% by weight, like the CPVC pipe or CPVC joint according to Invention III-3, Invention III-6, Invention III-9, Invention III-12, Invention III-15 and Invention III-18.
The particle structure of the CPVC to be used in producing the CPVC plate according to Invention III-21, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe, CPVC joint and CPVC plate of the invention.
The CPVC to be used in producing the CPVC plate according to Invention III-21, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe or CPVC joint according to Invention III-3, Invention III-6, Invention III-9, Invention III-12, Invention III-15 and Invention III-18.
The CPVC plate according to Invention III-21 can be molded in the same manner as the above-mentioned CPVC plate of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe and CPVC plate of the invention.
The gist of Invention III-21 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC plate having a Vicat softening temperature of not lower than 170xc2x0 C.
The CPVC plate according to Invention III-22 has a Vicat softening temperature of not lower than 145xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The Charpy impact strength is an indicator of the shock resistance of a resin plate and, when the Charpy impact strength is not less than 10 kgfxc2x7cm/cm2, the plate is suited for use for holding chemical fluids at 100xc2x0 C. or above.
The chlorine content of the CPVC plate according to Invention III-22 is preferably 70 to 76% by weight, like the CPVC pipe, CPVC joint or CPVC plate according to Invention III-1, Invention III-4, Invention III-7, Invention III-10, Invention III-13, Invention III-16 and Invention III-19.
The particle structure of the CPVC to be used in producing the CPVC plate according to Invention III-22, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe, CPVC joint and CPVC plate of the invention.
The CPVC to be used in producing the CPVC plate according to Invention III-22, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe, CPVC joint or CPVC plate according to Invention III-1, Invention III-4, Invention III-7, Invention III-10, Invention III-13, Invention III-16 and Invention III-19.
The CPVC plate according to Invention III-22 can be molded in the same manner as the above-mentioned CPVC plate of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe, CPVC joint and CPVC plate of the invention.
The gist of Invention III-22 consists in formulating CPVC having a chlorine content of 70 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC plate having a Vicat softening temperature of not lower than 145xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The CPVC plate according to Invention III-23 has a Vicat softening temperature of not lower than 155xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2 as determined by the method according to JIS K 7111.
The chlorine content of CPVC plate according to Invention III-23 is preferably 72 to 76% by weight, like the CPVC pipe, CPVC joint or CPVC plate according to Invention III-2, Invention III-5, Invention III-8, Invention III-11, Invention III-14, Invention III-17 and Invention III-20.
The particle structure of the CPVC to be used in producing the CPVC plate according to Invention III-23, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe, CPVC joint and CPVC plate of the invention.
The CPVC to be used in producing the CPVC plate according to Invention III-23, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe, CPVC joint or CPVC plate according to Invention III-2, Invention III-5, Invention III-8, Invention III-11, Invention III-14, Invention III-17 and Invention III-20.
The CPVC plate according to Invention III-23 can be molded in the same manner as the above-mentioned CPVC plate of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe, CPVC joint and CPVC plate of the invention.
The gist of Invention III-23 consists in formulating CPVC having a chlorine content of 72 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC plate having a Vicat softening temperature of not lower than 155xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The CPVC plate according to Invention III-24 has a Vicat softening temperature of not lower than 170xc2x0 C. as determined under a load of 1 kgf by the method according to JIS K 7206 and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm as determined by the method according to JIS K 7111.
The chlorine content of CPVC plate according to Invention III-24 is preferably 74 to 76% by weight, like the CPVC pipe, CPVC joint or CPVC plate according to Invention III-3, Invention III-6, Invention III-9, Invention III-12, Invention III-15, Invention III-18 and Invention III-21.
The particle structure of the CPVC to be used in producing the CPVC plate according to Invention III-24, too, is characterized by its particle inside structure and surface structure, like the CPVC to be used in producing the above-mentioned CPVC pipe, CPVC joint and CPVC plate the invention.
The CPVC to be used in producing the CPVC plate according to Invention III-24, too, can be obtained in the same manner as the CPVC to be used in producing the CPVC pipe, CPVC joint or CPVC plate according to Invention III-3, Invention III-6, Invention III-9, Invention III-12, Invention III-15, Invention III-18 and Invention III-21.
The CPVC plate according to Invention III-24 can be molded in the same manner as the above-mentioned CPVC plate of the invention using the same compounding additives as mentioned hereinabove referring to the CPVC pipe, CPVC joint and CPVC plate of the invention.
The gist of Invention III-24 consists in formulating CPVC having a chlorine content of 74 to 76% by weight and having a specific particle inside structure and a specific particle surface structure and molding the resulting compound. In this way, it becomes possible to provide a highly heat-resistant CPVC plate having a Vicat softening temperature of not lower than 170xc2x0 C. and a Charpy impact strength of not less than 10 kgfxc2x7cm/cm2.
The fourth aspect of the invention is now described in detail.
The term xe2x80x9cheat resistance temperaturexe2x80x9d as used herein referring to Inventions IV-1 to IV-4 is synonymous as xe2x80x9cVicat softening temperaturexe2x80x9d. It is determined by measuring Vicat softening temperature by the method of JIS K 7206 (weight 1.0 kgf, rate of temperature rise 50xc2x0 C./hour) using test specimens prepared by cutting a molding to be tested to 10 mmxc3x9710 mm.
As the heat-resistant vinyl chloride resin to be used in producing the heat-resistant vinyl chloride resin molding and heat-resistant vinyl chloride resin pipe according to Inventions IV-1 to IV-4, there may be mentioned CPVC obtainable by chlorinating PVC. The PVC prior to chlorination to CPVC, which is used in the practice of Inventions IV-1 to IV-4, preferably has a BET specific surface area of 1.3 to 8.0 m2/g and a carbon element-chlorine element 1S bond energy (eV) peak ratio (chlorine element peakxc3x972/carbon element peak) of above 0.6 as determined in particle surface analysis by ESCA (electron spectroscopy for chemical analysis).
When the BET specific surface area is less than 1.3 m2/g, the proportion of micropores not more than 0.1 xcexcm in size in the interior of PVC particles is insufficient to attain uniform chlorination and heat stability improvement. Further, the rate of gelation is slow and this is unfavorable from the molding viewpoint. When the BET specific surface area is in excess or 8 m2/g, the heat stability of PVC particles themselves before chlorination is low and the CPVC obtained becomes poor in workability. A BET specific surface area preferred for the PVC is within the range of 1.5 to 5 m2/g.
When the carbon element-chlorine element 1S bond energy (eV) peak ratio is 0.6 or below, an additive, for example a dispersant, supposedly occur in adsorbed form on the PVC particle surface and, therefore, not only the rate of chlorination in the subsequent step becomes slow but also the CPVC obtained may offer a moldability/fabricability problem and will have poor heat stability. More preferably, the above peak ratio should be above 0.7.
Among PVC species for which the above peak ratio is above 0.6, there exist skinless PVCs having a small skin surface area on the PVC particle surface. At the same energy ratio, skinless PVCs are preferably used.
The element occurrence ratio in the chemical structure of the above PVC is chlorine element:carbon element =1:2 (without considering the terminal structure and branching) and the above-mentioned peak ratio (chlorine element peakxc3x972/carbon element peak) at the 1S bond energy value (eV) has a value of 0 to 1. As discussed hereinabove referring to the first aspect and second aspect of the invention, the peak ratio value of 0 means that the surface of PVC particles is covered with some chlorine-free substance other than PVC, while the peak ratio value of 1 means that the surface of PVC particles is wholly covered with vinyl chloride components alone.
In the conventional process for producing CPVCs, no attention has been paid to the surface condition of PVC particles to be chlorinated and, accordingly, no attention has been paid to the chlorination degree distribution in the CPVC obtained. According to Inventions IV-1 to IV-4, heat-resistant vinyl chloride resin moldings having good heat resistance and smoothness are produced by paying due attention to the surface condition of PVC, which has an influence on the chlorination degree distribution of the CPVC.
The above PVC is a resin produced by polymerizing VCM alone or a mixture of VCM and another or other monomers copolymerizable with VCM in the conventional manner (e.g. suspension polymerization, bulk polymerization). The other monomers copolymerizable with VCM are not particularly restricted but include, among others, alkyl vinyl esters such as vinyl acetate; xcex1-monoolefins such as ethylene and propylene; vinylidene chloride; styrene and the like. These may be used singly or two or more of them may be used in combination.
The viscosity average degree of polymerization of the above PVC is not critical but may be within the conventional range of 400 to 2,000.
The viscosity average degree of polymerization is determined by the measurement method according to JIS K 6721.
The method of chlorinating the above PVC is not particularly restricted but may be any of the methods known in the art. For example, the chlorination can be effected by contacting chlorine with the PVC after setting a state suspended or dissolved in a solvent or in a solid state. The degree of chlorination of the CPVC obtained by the above chlorination reaction is not particularly restricted provided that the molding produced by using that CPVC show a heat resistance temperature of not lower than 125xc2x0 C.
In molding the heat-resistance vinyl chloride resin moldings or heat-resistance vinyl chloride resin pipes according to Inventions IV-1 to IV-4, compounding additives generally used in vinyl chlorine resins, such as stabilizers, lubricants, pigments, modifiers, antistatic agents and fillers, may be incorporated as necessary unless they defeat the objects of the invention.
The molding machine to be used in producing the moldings or resin pipes according to Inventions IV-1 to IV-4 is not particularly restricted but, for example, the molding can be effected by using a single-screw extruder, twin-screw two-directional parallel extruder, twin-screw two-directional conical extruder or twin-screw one-directional extruder or the like.
The mold, resin temperature and molding conditions in shaping the moldings or resin pipes according to Inventions IV-1 to IV-4 are not particularly restricted provided that the moldings obtained show a surface roughness kmax of not more than 0.5 xcexcm. For constantly obtaining moldings with smoothness, however, the surface roughness of the molding is preferably such that the Rmax is not more than 5 xcexcm and the Ra is not more than 0.2 xcexcm. For that purpose, such surface treatment as chromium plating may have been given. The mold lip L/D ratio (L: lip length, D: port thickness) is preferably not less than 15.
The temperature at the mold tip is not particularly restricted, either. From the heat stability and long run viewpoint, the molding is preferably carried out within the temperature range of [190 +(txe2x88x92120)/2] C. to [220+(txe2x88x92120)]xc2x0 C. where t (xc2x0C.) is the heat resistance temperature of the moldings.
The smoothness of the molding becomes better with the increase in resin temperature unless problems are encountered on the levels of degradation, long-run operability and physical properties. From the heat stability and long run viewpoint, however, it is preferred that the molding be carried out within the temperature range of [195 +(txe2x88x92120)/2]xc2x0 C. to [210 +(txe2x88x92120)]xc2x0 C. where t (xc2x0C.) is the heat resistance temperature of the molding.
The heat-resistant vinyl chloride resin molding according to Invention IV-2 and the heat-resistant vinyl chloride resin pipe according to Invention IV-4 are further characterized by a decomposition time of not shorter than 30 minutes as determined in an oven at 200xc2x0 C. The xe2x80x9cdecomposition time of not shorter than 30 minutesxe2x80x9d means that when a test specimen is allowed to stand in an oven at 200xc2x0 C., such a phenomenon as foaming, darkening or discoloration will not occur in a time period shorter than 30 minutes. The reason why the decomposition time is restricted to not shorter than 30 minutes is that when the molding temperature is raised significantly, moldings having a heat resistance temperature not lower than 125xc2x0 C. and an inside surface roughness Rmax of not more than 0.5 xcexcm may be obtained but for a while but it becomes somewhat difficult to mold such products continuously over several hours and that, for enabling several hours of long run molding, the residual heat stability of molded products in an oven at 200xc2x0 C. should be not shorter than 30 minutes as expressed in terms of decomposition time.
The heat-resistant vinyl chloride resin molding according to Invention IV-1 has a heat resistance temperature of not lower than 125xc2x0 C. and a surface roughness Rmax of not more than 0.5 xcexcm and therefore can be used at higher temperatures and, further, at higher pressure and stress, as compared with the prior art products having surface smoothness, hence the reliability can be markedly improved under the same use conditions.
Further, according to Invention IV-1, the resin itself can contribute to manifestation of good smoothness and, for attaining a surface roughness Rmax of not more than 0.5 xcexcm, it is now not necessary to significantly raise the resin temperature and mold temperature. As a result, smoothness can be provided while the long run operability and heat stability are maintained.
The heat-resistant vinyl chloride resin molding according to Invention IV-2 produces all the effects of the above-mentioned heat-resistant vinyl chloride resin molding according to Invention IV-1 and further, with the heat-resistant vinyl chloride resin molding according to Invention IV-2, the resin itself can contribute to manifestation of good smoothness and, attaining a surface roughness Rmax of not more than 0.5 xcexcm does not involve significantly increase in the resin temperature and mold temperature. Therefore, the molding has good residual heat stability (decomposition time) and it is possible to provide smoothness while the long run operability is maintained longer.
The heat-resistant vinyl chloride resin pipe according to Invention IV-3 has a heat resistance temperature of not lower than 125xc2x0 C., so that it can be used at still higher temperatures and at a higher pressure and stress as compared with the conventional vinyl chloride resin pipes and, under the same use conditions, the reliability can be markedly improved. Since its inside surface roughness Rmax is not more than 0.5 xcexcm, the proliferation of bacteria and other microorganisms in the pipe can be inhibited.
Further, according to Invention IV-3, the resin itself can contribute to good smoothness manifestation and, attaining a surface roughness Rmax of not more than 0.5 xcexcm does not involve significantly increase in the resin temperature and mold temperature. As a result, smoothness can be provided while the long run operability and heat stability are maintained.
The heat-resistant vinyl chloride resin pipe according to Invention IV-4 produces all the effects of the above-mentioned heat-resistant vinyl chloride resin molding according to Invention IV-2 and, further, the inside surface roughness Rmax thereof is not more than 0.5 xcexcm, bacteria and other microorganisms can be inhibited from propagating in the pipe. Furthermore, the elution of metals is slight and the pipe has smoothness as well, so that it is best suited for use as a piping material for ultrapure water.
The heat-resistant vinyl chloride resin pipe according to Invention IV-5 is produced by molding a heat-resistant vinyl chloride resin obtained by chlorinating a vinyl chloride resin having a viscosity average degree of polymerization of 900 to 1, 100 to a chlorine content of 66.0 to 67.5% by weight.
The heat-resistant vinyl chloride resin to be used in producing the heat-resistant vinyl chloride resin pipe according to Invention IV-5 is limited to CPVC obtained by chlorinating PVC. The surface condition, particle structure or the like of the PVC before chlorination to the CPVC to be used in the practice of Invention IV-5 is not particularly restricted.
The above-mentioned PVC is a resin produced by polymerizing VCM alone or a mixture of VCM and one or more other monomers copolymerizable with VCM in the conventional manner (e.g. by suspension polymerization, bulk polymerization). The other monomers copolymerizable with VCM are not particularly restricted but include, among others, alkyl vinyl esters such as vinyl acetate; xcex1-monoolefins such as ethylene and propylene; vinylidene chloride; styrene and the like. These may be used singly or two or more of them may be used combinedly.
The viscosity average degree of polymerization of the above PVC is restricted to 900 to 1, 100. When the viscosity average degree of polymerization is less than 900, the SC resistance will become low and it will be impossible to produce resin pipes having sufficient fatigue strength. When it is above 1, 100, the problem of decreased smoothness or unevenness may arise. The viscosity average degree of polymerization is measured by the method according to JIS K 6721.
The method of chlorinating the above PVC is not particularly restricted but any of the methods known in the art can be used. For example, the chlorination can be effected by contacting chlorine with the PVC after setting a state suspended or dissolved in a solvent or in a solid state.
The chlorine content (degree of chlorination) of the CPVC obtained by the chlorination reaction is restricted to 66.0 to 67.5% by weight. When the chlorine content is less than 66.0% by weight, satisfactory heat resistance can no more obtained and when it is above 67.5%, lowered SC resistance, decreased smoothness and inside surface unevenness, among others, may cause problems. The chlorine content is determined by the method according to JIS K 7229.
In molding the resin pipe in the practice of Invention IV-5, compounding additives generally used in vinyl chloride resins, such as stabilizers, lubricants, pigments, modifiers, antistatic agents, fillers and the like, may be incorporated when necessary in amounts which will not defeat the objects of the invention.
The molding machine to be used in producing the resin pipe according to Inventions IV-5 is not particularly restricted but, for example, the molding can be effected by using a single-screw extruder, twin-screw two-directional parallel extruder, twin-screw two-directional conical extruder or twin-screw one-directional extruder or the like.
The mold, resin temperature and molding conditions in molding the resin pipe according to Inventions IV-5 are not particularly restricted. For constantly obtaining moldings with smoothness, however, the surface roughness of the mold is preferably such that the Rmax is not more than 5 xcexcm and the Ra is not more than 0.2 xcexcm. For that purpose, such surface treatment as chromium plating may have been given. The mold lip L/D ratio (L: lip length, D: port thickness) is preferably not less than 15.
The temperature at the mold tip is not particularly restricted, either. From the heat stability and long run viewpoint, the molding is preferably carried out within the temperature range of [190 +(txe2x88x92120)/2]xc2x0 C. to [220 +(txe2x88x92120)]xc2x0 C. where t (xc2x0C.) is the heat resistance temperature of the resin pipe.
The smoothness of the resin pipe becomes better with the increase in resin temperature unless problems are encountered on the levels of degradation, long-run operability and physical properties. From the heat stability and long run viewpoint, however, it is preferred that the molding be carried out within the temperature range of [195 +(txe2x88x92120)/2]xc2x0 C. to [210 +(txe2x88x92120)]xc2x0 C. where t (xc2x0C.) is the heat resistance temperature of the resin pipe.
The heat-resistant vinyl chloride resin pipe according to Invention IV-5 has a surface roughness Pmax of not more than 0.5 xcexcm, without involving significant increases in resin temperature and mold temperature, since the resin itself can contribute to good smoothness manifestation. Therefore, the heat-resistant vinyl chloride resin pipe according to Invention IV-5 has good residual heat-stability and has been provided with smoothness, with the long run operability and heat stability being maintained. Accordingly, the heat-resistant vinyl chloride resin pipe according to Invention IV-5 is judiciously used, among others, as a piping Material for ultrapure water supply for plant use, where good smoothness, heat resistance and SC resistance are simultaneously required.
The heat-resistant vinyl chloride resin pipe according to Invention IV-6 is a heat-resistant vinyl chloride resin pipe according to Invention IV-3, Invention IV-4 or Invention IV-5 which is to serve as a piping material for pure water distribution.
The heat-resistant vinyl chloride resin pipe according to Invention IV-6 has a surface roughness Rmax of not more than 0.5 xcexcm, without involving significant increases in resin temperature and mold temperature since the resin itself can contribute to good smoothness manifestation. Therefore, the heat-resistant vinyl chloride resin pipe according to Invention IV-6 has been provided with smoothness, with the long run operability and heat stability be maintained. Accordingly, the heat-resistant vinyl chloride resin pipe according to Invention IV-6 is judiciously used as a piping material for pure water supply, among others.